Pressure resistant and corrosion resistant copper alloy, brazed structure, and method of manufacturing brazed structure

ABSTRACT

A pressure resistant and corrosion resistant copper alloy contains 73.0 mass % to 79.5 mass % of Cu and 2.5 mass % to 4.0 mass % of Si with a remainder composed of Zn and inevitable impurities, in which the content of Cu [Cu] mass % and the content of Si [Si] mass % have a relationship of 62.0≦[Cu]−3.6×[Si]≦67.5. In addition, the area fraction of the α phase “α”%, the area fraction of a β phase “β”%, the area fraction of a γ phase “γ”%, the area fraction of the κ phase “κ”%, and the area fraction of a μ phase “μ”% satisfy 30≦“α”≦84, 15≦“κ”≦68, “α”+“κ”≧92, 0.2≦“κ”/“α”≦2, “β”≦3, “μ”≦5, “β”+“μ”≦6, 0≦“γ”≦7, and 0≦“β”+“μ”+“γ”≦8. Also disclosed is a method of manufacturing a brazed structure made of the above pressure resistant and corrosion resistant copper alloy.

This is a Continuation-in-Part application in the United States ofInternational Patent Application No. PCT/JP2011/074389 filed Oct. 24,2011, which claims priority on Japanese Patent Application No.2010-238311, filed Oct. 25, 2010. The entire disclosures of the abovepatent applications are hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a pressure resistant and corrosionresistant copper alloy brazed to another material, a brazed structurehaving a pressure resistant and corrosion resistant copper alloy, and amethod of manufacturing a brazed structure, and particularly to apressure resistant and corrosion resistant copper alloy having highpressure resistance and excellent corrosion resistance, and the like.

BACKGROUND OF THE INVENTION Background Art

Examples of containers, devices, and members for high-pressure gasfacilities, air-conditioning facilities, cold and hot-water supplyequipment, and the like include a variety of valves including ahigh-pressure valve, a variety of joints, hydraulic containers such as avariety of valves, joints and cylinders, nozzles, sprinklers, waterfaucet clasps, and the like, and a copper alloy used for the above isjoined with a copper pipe, a variety of members, and the like. Since ahigh pressure is applied to the joint portion, brazing is employed as ajoining method from the viewpoint of reliability. Brazing produces ahigh joint strength and a high reliability, but the melting point of abrazing is high, approximately 700° C. to 830° C., and therefore acopper alloy to be brazed is also, accordingly, heated to a temperatureof the melting point of the brazing or higher. However, since a copperalloy used for the above members generally has a melting point ofapproximately 850° C. to 950° C., there is a problem in that thematerial strength of a brazed copper alloy significantly decreases, andcorrosion resistance degrades.

The above copper alloy is a cut hot-forged material, a cut extruded rodmaterial, or a cut material of a cast metal and a continuously cast rod.Examples of the hot-forged material or the extruded rod material includea forging brass rod C3771 that is mainly based on JIS H 3250 standardsand is excellent in terms of hot forgeability (typical composition:59Cu−2Pb-remainder: Zn), a free-cutting brass C3604 that is excellent incutting work (typical composition: 59Cu−3Pb-remainder: Zn), a copperalloy material obtained by substituting Pb in the above materials withBi due to a recent demand for removing Pb, and dezincification corrosionresistant forging brass or dezincification corrosion resistantfree-cutting brass in which the concentration of copper is increased to61 mass % to 63 mass % in order to obtain excellent dezincificationresistance.

Meanwhile, examples of the cast metal include CAC406 (85Cu−5Sn−5Zn−5Pb)which is a cast metal based on the standards of JIS H 5120 or JIS H 5121or a continuously forged cast and a Cu—Sn—Zn—Pb alloy that is excellentin terms of corrosion resistance, a Cu—Sn—Zn—Bi alloy obtained bysubstituting Pb in the above alloy with Bi, brass cast metal CAC202(67Cu−1Pb-remainder: Zn) that is excellent in terms of mold castability,CAC203 (60Cu−1Pb-remainder: Zn), and the like. However, when the abovecopper alloy is brazed, since the copper alloy is heated to a hightemperature of approximately 800° C. or approximately 750° C., or atleast 700° C. or higher, there is a problem in that the materialstrength decreases. Particularly, in a Cu—Zn alloy containing Pb, Bi,Sn, and the like, when the Cu concentration exceeds 64 mass %, thecrystal grains coarsen such that the strength significantly decreases.In addition, the CAC406 alloy has a high Cu concentration, has had aproblem of a low strength, and, furthermore, has a problem in that thestrength decreases further. Meanwhile, when an alloy having 63 mass % orless of Cu, particularly, a Cu—Zn—Pb or Cu—Zn—Bi alloy is heated to atemperature of 700° C. or higher, particularly 800° C. or higher, thefraction of a 13 phase increases, and a problem occurs with thecorrosion resistance. Furthermore, in a case in which the Cuconcentration is low, since the fraction of the 13 phase increases,ductility or impact characteristics decrease.

General examples of a brazing material used for joining of a copperalloy such as a valve and a copper pipe or the like include a phosphorbronze brazing filler of JIS Z 3264 and a silver solder of JIS Z 3261.Among the above, a phosphor bronze brazing filler of BCuP-2 (typicalcomposition: 7% P-93% Cu) is most frequently used, and a phosphor bronzebrazing filler of BCuP-3 (typical composition: 6.5% P-5% Ag-88.5% Cu)and a silver solder of Bag-6 (typical composition: 50% Ag-34% Cu−16% Zn)are also frequently used. The melting points (solidustemperature-liquidus temperature) of the brazing filler metals are 710°C. to 795° C., 645° C. to 815° C., and 690° C. to 775° C. respectively,and the brazing temperatures are reported to be 735° C. to 845° C., 720°C. to 815° C., and 775° C. to 870° C. respectively in JIS standards.Therefore, while also depending on the kind of the brazing filler metaland the shape, thickness, and size of the copper alloy, the copper alloysuch as a valve is heated to at least 700° C. or higher, approximately800° C. over several seconds to several minutes, and non-directly heatedportions also reach a high-temperature state. When the copper alloy isheated to at least 700° C. or higher, approximately 800° C., the aboveproblem regarding pressure resistance or corrosion resistance occurs.Further, as a brazing method, there is a method in which a brazingfiller metal is placed in a joint portion, and made to pass through afurnace heated to approximately 800° C., thereby performing continuousbrazing. In this case, the entire copper alloy such as a valve is heatedto 800° C., and cooled.

In addition, although not relating to characteristics after brazing, asa technique that decreases the β phase which degrades corrosionresistance, a technique in which a Bi-added free-cutting copper alloycomposed of 60.0 mass % to 62.5% Cu, 0.4 mass % to 2.0 mass % Bi and0.01 mass % to 0.05 mass % P with a remainder of Zn is hot-extruded,then slowly cooled so that the surface temperature of the extrudedmaterial becomes 180° C. or lower, then a thermal treatment is carriedout at, for example, 350° C. to 550° C. for 1 hour to 8 hours so as todecrease the β phase and form a metallic structure in which the vicinityof the β phase is surrounded by an a phase, thereby securing favorablecorrosion resistance is known (for example, refer to Japanese UnexaminedPatent Application Publication No. 2008-214760). When the copper alloyis worked at a high temperature, since the amount of the β phaseincreases, corrosion resistance is secured by adding a slow coolingprocess after hot working as described above, and, furthermore, athermal treatment process after cooling. However, in brazing, such slowcooling or a thermal treatment after cooling definitely leads to anincrease in costs, and there is a problem in that the thermal treatmentis difficult practically.

-   [Patent Document 1] Japanese Unexamined Patent Application    Publication No. 2008-214760.

SUMMARY OF THE INVENTION

The invention has been made in order to solve the above problems of therelated art, and an object of the invention is to provide a pressureresistant and corrosion resistant copper alloy brazed to anothermaterial that has high pressure resistance and excellent corrosionresistance.

In order to solve the above problems, the present inventors studied thecompositions and metallic structures of copper alloys. As a result, itwas found that high pressure resistance and excellent corrosionresistance can be obtained by setting the area fractions of therespective phases in the metallic structure within a predetermined rangein a copper alloy having a predetermined composition.

Specifically, it was found that high pressure resistance and excellentcorrosion resistance can be obtained in a case in which a copper alloyhas an alloy composition containing 73.0 mass % to 79.5 mass % of Cu and2.5 mass % to 4.0 mass % of Si with a remainder composed of Zn andinevitable impurities, the content of Cu [Cu] mass % and the content ofSi [Si] mass % have a relationship of 62.0≦[Cu]−3.6×[Si]≦67.5, and themetallic structure at the brazed portion of the copper alloy includes atleast a κ phase in an α phase matrix, and the area fraction of the αphase “α”%, the area fraction of a β phase “β”%, the area fraction of aγ phase “γ”%, the area fraction of the κ phase “κ”%, and the areafraction of a μ phase “μ”% satisfy 30≦“α”≦84, 15≦“κ”≦68, “α”+“κ”≧92,0.2≦“κ”/“α”≦2, 0≦“β”≦3, 0≦“μ”≦5, 0≦“β”+“μ”≦6, 0≦“γ”≦7, and0≦“β”+“μ”+“γ”8. Further, the brazed portion refers to a portion heatedto 700° C. or higher during brazing.

The invention has been completed based on the above finding of theinventors. That is, in order to solve the above problems, the inventionprovides a pressure resistant and corrosion resistant copper alloybrazed to another material having an alloy composition containing 73.0mass % to 79.5 mass % of Cu and 2.5 mass % to 4.0 mass % of Si with aremainder composed of Zn and inevitable impurities, in which the contentof Cu [Cu] mass % and the content of Si [Si] mass % have a relationshipof 62.0≦[Cu]−3.6×[Si]≦67.5, the metallic structure at the brazed portionof the copper alloy includes at least a κ phase in an α phase matrix,and the area fraction of the α phase “α”%, the area fraction of a βphase “β”%, the area fraction of a γ phase “γ”%, the area fraction ofthe κ phase “κ”%, and the area fraction of a μ phase “μ”% satisfy30≦“α”≦84, 15≦“κ”≦68, “α”+“κ”≧92, 0.2≦“κ”/“α”≦2, 0≦“β”≦3, 0≦“μ”5,0≦“β”+“μ”≦6, 0≦“γ”≦7, and 0≦“β”+“μ”+“γ”8. The pressure resistant andcorrosion resistant copper alloy brazed to another material can havehigh pressure resistance and excellent corrosion resistance.

Preferably, the copper alloy further contains at least one of 0.015 mass% to 0.2 mass % of P, 0.015 mass % to 0.2 mass % of Sb, 0.015 mass % to0.15 mass % of As, 0.03 mass % to 1.0 mass % of Sn, and 0.03 mass % to1.5 mass % of Al, and the content of Cu [Cu] mass %, the content of Si[Si] mass %, the content of P [P] mass %, the content of Sb [Sb] mass %,the content of As [As] mass %, the content of Sn [Sn] mass %, and thecontent of Al [Al] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.

Since the copper alloy has at least one of P, Sb, As, Sn, and Al, thecorrosion resistance becomes more favorable.

Preferably, the copper alloy further contains at least one of 0.015 mass% to 0.2 mass % of P, 0.015 mass % to 0.2 mass % of Sb, 0.015 mass % to0.15 mass % of As, and at least one of 0.3 mass % to 1.0 mass % of Snand 0.45 mass % to 1.2 mass % of Al, and the content of Cu [Cu] mass %,the content of Si [Si] mass %, the content of P [P] mass %, the contentof Sb [Sb] mass %, the content of As [As] mass %, the content of Sn [Sn]mass %, and the content of Al [Al] mass % satisfy63.5≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.

Since the copper alloy contains 0.3 mass % or more of Sn or 0.45 mass %or more of Al, the erosion and corrosion resistance becomes favorable.

Preferably, the copper alloy further contains at least one of 0.003 mass% to 0.25 mass % of Pb and 0.003 mass % to 0.30 mass % of Bi, and thecontent of Cu [Cu] mass %, the content of Si [Si] mass %, the content ofP [P] mass %, the content of Sb [Sb] mass %, the content of As [As] mass%, the content of Sn [Sn] mass %, the content of Al [Al] mass %, thecontent of Pb [Pb] mass %, and the content of Bi [Bi] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]≦67.5.

Since the copper alloy includes at least one of Pb and Bi, themachinability becomes favorable.

Preferably, the copper alloy further contains at least one of 0.05 mass% to 2.0 mass % of Mn, 0.05 mass % to 2.0 mass % of Ni, 0.003 mass % to0.3 mass % of Ti, 0.001 mass % to 0.1 mass % of B, and 0.0005 mass % to0.03 mass % of Zr, and the content of Cu [Cu] mass %, the content of Si[Si] mass %, the content of P [P] mass %, the content of Sb [Sb] mass %,the content of As [As] mass %, the content of Sn [Sn] mass %, thecontent of Al [Al] mass %, the content of Pb [Pb] mass %, the content ofBi [Bi] mass %, the content of Mn [Mn] mass %, the content of Ni [Ni]mass %, the content of Ti [Ti] mass %, the content of B [B] mass %, andthe content of Zr [Zr] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]+2×[Mn]+1.7×[Ni]+1×[Ti]+2×[B]+2×[Zr]≦67.5.

Since the copper alloy contains at least one of Mn, Ni, Ti, B, and Zr,the strength further improves.

Preferably, the copper alloy has a material strength of 400 N/mm² ormore in terms of tensile strength or 150 N/mm² or more in terms of proofstress.

Since the copper alloy has a high material strength, it is possible toreduce the costs through a decrease in the thickness and the like.

The invention provides a brazed structure having any of the abovepressure resistant and corrosion resistant copper alloys, anothermaterial brazed to the copper alloy, and a brazing filler metal thatbrazes the copper alloy and the another material. Further, an integratedarticle of the brazed copper alloy, the other material, and the brazingfiller metal is referred to as a brazed structure.

Since the strength of the copper alloy is high, the pressure resistanceof the brazed structure increases.

In addition, the inventors studied brazing methods. In Cu—Zn alloys ofthe related art or Patent Document 1, the β phase was decreased bybringing the copper alloy to a high temperature state through brazing orthe like and then slowly cooling the copper alloy, or performing athermal treatment for a long period of time at a temperature lower thanthe brazing temperature; however, as a result of the studies of thistime, it was found that, in the copper alloy according to the inventionhaving the above composition, when the cooling rate after the brazing isset within a predetermined range, the metallic structure at the brazedportion includes at least the κ phase in the α phase matrix, and thearea fraction of the α phase “α”%, the area fraction of the β phase“β”%, the area fraction of the γ phase “γ”%, the area fraction of the κphase “κ”%, and the area fraction of the μ phase “μ”% satisfy 30≦“α”≦84,15≦“κ”≦68, “α”+“κ”≧92, 0.2≦“κ”/“α”≦2, 0≦“β”≦3, 0≦“μ”5, 0≦“β”+“μ”≦6,0≦“γ”≦7, and 0≦“β”+“μ”+“γ”≦8 even without the above special thermaltreatment. That is, the invention provides a method of manufacturing thebrazed structure, in which, in a state in which the brazing filler metalis interposed between the copper alloy and the other material, thebrazed portion of the copper alloy, the brazed portion of the othermaterial, and the brazing filler metal are heated to at least 700° C. orhigher so as to be brazed, and the brazed portion of the copper alloy iscooled at an average cooling rate of 0.1° C./second to 60° C./second ina temperature range from the material temperature when brazing ends to300° C., or from 700° C. to 300° C.

The area fractions of the respective phases, such as the α phase and theβ phase in the metallic structure, become within the above ranges, andhigh pressure resistance and excellent corrosion resistance can beobtained.

In addition, the invention provides a method of manufacturing the brazedstructure, in which, in a state in which the brazing filler metal isinterposed between the copper alloy and the other material, the brazedportion of the copper alloy, the brazed portion of the other material,and the brazing filler metal are heated to at least 750° C. or higher soas to be brazed, and the brazed portion of the copper alloy is cooled atan average cooling rate of 1.5° C./second to 40° C./second in atemperature range from the material temperature when brazing ends to300° C., or from 700° C. to 300° C.

The area fractions of the respective phases, such as the α phase and theβ phase in the metallic structure, become within the above ranges, andhigh pressure resistance and excellent corrosion resistance can beobtained.

Effects of the Invention

According to the present invention, in a pressure resistant andcorrosion resistant copper alloy brazed to another material, highpressure resistance and excellent corrosion resistance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are photos of the metallic structures of copper alloysaccording to embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION Best Mode for Carrying Out theInvention

A copper alloy according to the embodiment of the invention will bedescribed. As the copper alloy according to the invention, first tofourth invention alloys are proposed. In order to indicate an alloycomposition, in the present specification, an element symbol in aparenthesis of [ ] such as [Cu] represents the content (mass %) of thecorresponding element. In addition, in the specification, a plurality ofcomputation formulae is proposed using the method of indicating thecontent; however, in the computation formulae, elements that are notincluded are considered to be zero in computation. In addition, a symbolshowing a metallic structure in a parenthesis of “ ” such as “α”represents the area fraction (%) of the corresponding metallicstructure. In addition, the first to fourth invention alloys arecollectively referred to as the “invention alloys.”

The first invention alloy has an alloy composition containing 73.0 mass% to 79.5 mass % of Cu and 2.5 mass % to 4.0 mass % of Si with aremainder composed of Zn and inevitable impurities, in which the contentof Cu [Cu] mass % and the content of Si [Si] mass % have a relationshipof 62.0≦[Cu]−3.6×[Si]≦67.5.

The second invention alloy has the same composition ranges of Cu and Sias for the first invention alloy, and further contains at least one of0.015 mass % to 0.2 mass % of P, 0.015 mass % to 0.2 mass % of Sb, 0.015mass % to 0.15 mass % of As, 0.03 mass % to 1.0 mass % of Sn, and 0.03mass % to 1.5 mass % of Al, in which the content of Cu [Cu] mass %, thecontent of Si [Si] mass %, the content of P [P] mass %, the content ofSb [Sb] mass %, the content of As [As] mass %, the content of Sn [Sn]mass %, and the content of Al [Al] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.

The third invention alloy has the same composition ranges of Cu, Si, P,Sb, As, Sn, and Al as for the first or second invention alloy, andfurther contains at least one of 0.003 mass % to 0.25 mass % of Pb and0.003 mass % to 0.30 mass % of Bi, in which the content of Cu [Cu] mass%, the content of Si [Si] mass %, the content of P [P] mass %, thecontent of Sb [Sb] mass %, the content of As [As] mass %, the content ofSn [Sn] mass %, the content of Al [Al] mass %, the content of Pb [Pb]mass %, and the content of Bi [Bi] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]≦67.5.

The fourth invention alloy has the same composition ranges of Cu, Si, P,Sb, As, Sn, Al, Pb, and Bi as for the first, second, or third inventionalloy, and further contains at least one of 0.05 mass % to 2.0 mass % ofMn, 0.05 mass % to 2.0 mass % of Ni, 0.003 mass % to 0.3 mass % of Ti,0.001 mass % to 0.1 mass % of B, and 0.0005 mass % to 0.03 mass % of Zr,in which the content of Cu [Cu] mass %, the content of Si [Si] mass %,the content of P [P] mass %, the content of Sb [Sb] mass %, the contentof As [As] mass %, the content of Sn [Sn] mass %, the content of Al [Al]mass %, the content of Pb [Pb] mass %, the content of Bi [Bi] mass %,the content of Mn [Mn] mass %, the content of Ni [Ni] mass %, thecontent of Ti [Ti] mass %, the content of B [B] mass %, and the contentof Zr [Zr] mass % satisfy62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]+2×[Mn]+1.7×[Ni]+1×[Ti]+2×[B]+2×[Zr]≦67.5.

Next, the reasons why the respective elements are added will bedescribed. Cu is a major element that composes the present inventionalloy, and also has a relationship with Si. In a copper alloy afterbrazing, the content of Cu needs to be 73.0 mass % or more, is morepreferably 73.5 mass % or more, and is optimally 74.0 mass % or more inorder to prevent or suppress to the minimum extent appearance of a βphase which has an influence on the corrosion resistance, suppressprecipitation of a γ phase to a necessary amount, and have excellentpressure resistance, ductility, and impact characteristics afterbrazing. On the other hand, while the relationship with Si may have aneffect, even when Cu is included at more than 79.5 mass %, the corrosionresistance of a brazed copper alloy becomes saturated, conversely, aproblem occurs with the pressure resistance, and, furthermore, problemsoccur with castability, forgeability, and machinability when anon-brazed copper alloy is formed. The more preferable upper limit valueis 79.0 mass %.

Si is a major element that composes the invention alloy together with Cuand Zn. When the content of Si is less than 2.5 mass %, in a brazedcopper alloy, solid solution hardening through Si or formation of the κphase becomes insufficient, and therefore the pressure resistancedeteriorates, and a problem occurs with the corrosion resistance. Inaddition, the machinability deteriorates when a non-brazed copper alloyis formed. The content of Si is more preferably 2.7 mass % or more. Onthe other hand, even when Si is included at more than 4.0 mass %, thepressure resistance of a brazed copper alloy is saturated, and thefraction of the α phase decreases, and therefore ductility, corrosionresistance, and impact characteristics deteriorate. In addition, when anon-brazed copper alloy is formed, the fractions of the κ phase and theγ phase increase, and the fraction of the α phase decreases, andtherefore a problem occurs with machinability, castability, orforgeability. In addition, in a brazed metallic structure, the β phase,which is harmful to corrosion resistance and the like, becomes liable tobe formed, the μ phase and the γ phase increase, and corrosionresistance, ductility, and impact characteristics deteriorate. As aresult, the content of Si is more preferably 3.8 mass % or less.

P, Sb, and As are necessary to improve corrosion resistance. P, Sb, andAs all improve the corrosion resistance of the α phase, and particularlyAs and P have a large improvement effect. Meanwhile, Sb improves thecorrosion resistance of the κ phase, and also improves the corrosionresistance of the μ phase, the γ phase, and the β phase. P and Asimprove the corrosion resistance of the κ phase, but the effect issmaller than Sb, and the corrosion resistance of the μ phase, the γphase, and the β phase slightly improves. In addition, P refines thecrystal grains of a hot-forged product, refines the crystal grains of acast metal when added with Zr, and suppresses the growth of the crystalgrains even when the cast metal is brazed. In consideration of thepressure resistance and corrosion resistance of a cast metal or a forgedproduct after brazing, P or As and Sb are preferably added incombination. When the content of any of P, Sb, and As is less than 0.015mass %, the effect of improving corrosion resistance or strength issmall. Even when 0.15 mass % of As and 0.2 mass % or more of each of Sband P are included, the effect of corrosion resistance and the like issaturated, and the ductility after brazing is impaired.

Similarly to P, Sb, and As, Sn and Al are elements that improvecorrosion resistance after brazing, and improve corrosion resistanceparticularly in high-speed flowing water or flowing water in whichphysical actions particularly occur, that is, erosion and corrosionproperties, cavitation properties, and, furthermore, corrosionresistance under an environment of poor water quality. In addition, Snand Al harden the α phase and the κ phase, and thus improve pressureresistance and abrasion resistance. In order to improve corrosionresistance or strength, Sn needs to be included at 0.03 mass % or more,preferably 0.2 mass % or more, and optimally 0.3 mass % or more. On theother hand, when Sn is included at more than 1.0 mass %, the improvementeffect is saturated, the amount of the γ phase increases after brazing,and, conversely, elongation is impaired, and therefore Sn is included atmore preferably 0.8 mass % or less. In order to improve corrosionresistance and pressure resistance, Al needs to be included at 0.03 mass% or more, preferably 0.25 mass % or more, and optimally 0.45 mass % ormore. On the other hand, when Al is included at more than 1.5 mass %,the effect is almost saturated, castability or ductility is impaired,and ductility after brazing is impaired, and therefore Al is included atpreferably 1.2 mass % or less and optimally 0.9 mass % or less. Since Snand Al both have an effect of improving the corrosion resistance of therespective phases, and mainly improve corrosion resistance, erosionproperties, cavitation properties, and the like, in flowing water inwhich physical actions occur, in a case in which Sn and Al are includedas a more preferable embodiment, one or more of P, Sb, and As whichimprove the corrosion resistance of the α phase, the κ phase, the μphase, the γ phase, and the β phase are preferably included. Inaddition, when Sn is included at 0.3 mass % or more, or Al is includedin an amount in the optimal range of 0.45 mass % or more, and the copperalloy is cooled from a high temperature of 700° C. or 750° C. or higherat which brazing is performed, the fraction of the γ phase abruptlyincreases. The γ phase in an alloy containing a large amount of Sn andAl includes Sn and Al in an amount larger than the content of Sn and Alincluded in the alloy, that is, Sn and Al are more concentrated in the γphase. An increase in the γ phase in which Sn and Al are included at ahigh concentration improves erosion and corrosion properties and thelike, but degrades ductility or impact characteristics. In order tosatisfy both a significant improvement in erosion and corrosionproperties and high ductility, it is necessary to adjust the K valuedescribed below or the metallic structure of the phase ratio such as κ/αand the like.

Pb and Bi are added in a case in which a cutting process is performedwhen a valve or the like is molded, particularly a case in whichexcellent machinability is required. When predetermined amounts of Cu,Si, and Zn are mixed into the invention alloy, Pb and Bi exhibit theeffect from a content of 0.003 mass % or more respectively.

Meanwhile, since Pb is harmful to human bodies, Bi is a rare metal, and,furthermore, ductility or impact characteristics after brazingdeteriorate due to Pb and Bi, the content of Pb remains at 0.25 mass %or less. The content of Pb is preferably 0.15 mass % or less, and morepreferably 0.08 mass % or less. Similarly, since Bi is also a raremetal, the content of Bi is preferably 0.2 mass % or less, and morepreferably 0.1 mass % or less. Furthermore, the total content of acombination of Pb and Bi is preferably 0.25 mass % or less, and morepreferably 0.15 mass % or less. In addition, Pb and Bi are present asparticles without forming solid solutions in the matrix; however, whenPb and Bi are added together, both elements are present together suchthat the melting point of the combined material decreases, and there isa concern that the copper alloy may crack during a cooling process ofbrazing or cutting work of a material. In consideration of thecharacteristics of the coexisting particles of Pb and Bi, in a case inwhich both elements are included at 0.02 mass % or more respectively,7[Bi]/[Pb] is preferable, or 0.35[Bi]/[Pb] is preferable.

Mn and Ni form intermetallic compounds mainly with Si so as to improvepressure resistance and abrasion resistance after brazing. Therefore, Mnand Ni need to be added at 0.05 mass % or more respectively. On theother hand, when Mn and Ni are added at more than 2.0 mass %respectively, the effect is almost saturated, machinability degrades,and ductility and impact characteristics after brazing deteriorate.

Ti and B improve the strength of the copper alloy with addition of asmall amount. The strength is improved mainly by refining crystal grainsat a step of a forged product and a cast metal so as to suppress thegrowth of crystal grains even after brazing. Since the effect isexhibited when Ti is included at 0.003 mass % and B is included at 0.001mass % or more, the effect is saturated even when Ti is included at morethan 0.3 mass %, and B is included at more than 0.1 mass %, and,moreover, since Ti and B are active metals, inclusion of oxides becomesliable to occur during dissolution in the atmosphere, and therefore Tiis included at preferably 0.2 mass % or less, and B is included atpreferably 0.05 mass % or less.

Zr improves the strength of the copper alloy with addition of a smallamount. The strength is improved mainly in the following manner: crystalgrains are significantly refined at a step of a cast metal, and thecrystal grains remain in a fine state even after brazing so that a highstrength is obtained due to crystal grain refinement. The effect isexhibited when Zr is included at an extremely small amount of 0.0005mass % or more, the effect is saturated even when Zr is included at morethan 0.03 mass %, and, moreover, the refinement of crystal grains isimpaired. Further, the effect of crystal grain refinement by Zr isparticularly exhibited when P is added together, and the mixing ratio ofZr to P is important, and therefore the effect is more significantlyexhibited when 1≦[P]/[Zr]≦80 is satisfied.

Next, other impurities will be described. The copper alloy is excellentin terms of recyclability, is collected at a high recycling rate andrecycled, but there is a problem in that another copper alloy may beincorporated during recycling or Fe and the like may be inevitablyincorporated due to abrasion of a tool during, for example, cuttingwork. Therefore, with regard to elements standardized as impurities in avariety of standards such as JIS, the standards of impurities areapplied to the present alloy. For example, like the free-machiningcopper alloy rod C3601 described in copper and copper alloy rods of JISH 3250, 0.3 mass % or less of Fe is treated as an inevitable impurity.

Next, the relationships among the respective elements will be described.In the relationships of Cu and Si or selectively included P, Pb, and thelike in the copper alloy, in order to have a high strength even afterbrazing, have excellence in terms of impact characteristics orductility, and obtain a favorable metallic structure that has a largeinfluence on characteristics, when

K=[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]+2×[Mn]+1.7×[Ni]+1×[Ti]+2×[B]+2×[Zr],

the following formula 62.0≦K≦67.5 must be satisfied.

Furthermore, the coefficients of the respective elements are obtainedfrom experiment results, and, furthermore, in a case in which elementsother than the above, for example, Fe and the like, are inevitablyincluded, when the total of the contents of the impurities is 0.7 mass %or less, the elements may be considered to have no influence. Meanwhile,a preferable range is 62.7≦K≦66.8 considering the influence of theimpurities to the maximum extent. Furthermore, while the K value isinfluenced when the total of the contents of the impurities exceeds 0.7mass %, in a case in which the total of the contents of the impuritiesexceeds 0.7 mass %, when the total of the contents of the impurities isset to X mass %, the range may be set to 62.0+(X−0.7)≦K≦67.5−(X−0.7),that is, 61.3+X≦K≦68.2−X, and more preferably to 61.8+X≦K≦67.7−X. Whenthe K value is lower than 62.0, macro crystal grains coarsen duringhigh-temperature heating, the fraction of the β phase precipitating at ahigh temperature increases, and the β phase remains to a large extentregardless of the cooling rate. In addition, since formation of the γphase is accelerated, impact characteristics and ductility decrease, andcorrosion resistance also deteriorates. In addition, pressure resistanceand tensile strength also slightly decrease. When the K value is higherthan 67.5, the fraction of the α phase excessively increases, and, sincethe α phase originally has a low strength, and the crystal grains of theα phase grow during high-temperature heating, pressure resistance,tensile strength, and proof stress decrease. Due to the above facts,preferably, the K value has a lower limit side of preferably 62.5 ormore and optimally 63.0 or more, and an upper limit side of preferably67.0 or less and optimally 66.5 or less. In addition, in a case in which0.3 mass % or more of Sn and 0.45 mass % or more of Al are included, thelower limit side of the K value is preferably 63.5 or more, andoptimally 64.0 or more in consideration of impurities and the like.Since formation of a small amount of the γ phase increases the strength,the upper limit side may be 67.5 or less, and optimally 67.0 or less inconsideration of impurities and the like. As such, in order to haveexcellent characteristics even after brazing, a composition managementwithin a narrow range is required. Furthermore, when the total contentof Pb and Bi exceeds 0.003 mass %, impact characteristics, ductility,and tensile strength begin to decrease. Particularly, inclusion of Pband the like has a large influence on impact characteristics andductility, the range of the K value needs to be set to be narrow, and,particularly, a value on the lower limit value side must be increased.Therefore, in a case in which Pb and Bi are included, preferably62.0+3([Pb]+[Bi]−0.003)≦K≦67.5−2([Pb]+[Bi]−0.003), and more preferably62.5+3([Pb]+[Bi]−0.003)≦K≦67.0−2([Pb]+[Bi]−0.003). In addition, in acase in which cutting work is performed when a valve and the like aremolded, when the K value does not fall within a range of62.0+3([Pb]+[Bi]−0.003)≦K≦67.5−2([Pb]+[Bi]−0.003), excellentmachinability cannot be obtained with the small amount of Pb and/or theamount of Bi which are specified in the application.

Next, the metallic structure of the brazed portion after brazing will bedescribed. In order to obtain high pressure resistance, ductility,impact characteristics, and corrosion resistance after brazing, themetallic structure as well as the composition becomes important. Thatis, the brazed metallic structure includes at least the κ phase in the αphase matrix, and 30≦“α”≦84, 15≦“κ”≦68, “α”+“κ”≧92, 0.2≦“κ”/“α”≦2,“δ”≦3, “μ”≦5, “β”+“μ”6, 0≦“γ”≦7, and 0≦“β”+“μ”+“γ”8 are all satisfied.In the metallic structure, when the total of the area fraction of twomajor phases, the α phase and the κ phase is less than 92%, highpressure resistance, ductility, or impact characteristics cannot besecured, and corrosion resistance also becomes insufficient. Basicallythe a phase is the matrix, the α phase is very ductile andcorrosion-resistant, and the α phase is surrounded by the κ phase or theα phase and the κ phase are uniformly mixed into the brazed metallicstructure so that the crystal grain growth of both the α phase and the κphase is suppressed, high pressure resistance is obtained, and highductility, impact characteristics, and, at the same time, excellentcorrosion resistance are obtained. Further, in order to make the abovecharacteristics superior, preferably “α”+“κ”≧94, and most preferably“α”+“κ”≧95. In addition, the α phase and the κ phase preferably form ametallic structure in which the α phase is surrounded by the κ phase orthe α phase and the κ phase are uniformly mixed, and are important toobtain high pressure resistance, high ductility, impact characteristics,and excellent corrosion resistance. That is, when “κ”/“α” is less than0.2, the α phase becomes excessive, and ductility, corrosion resistance,and impact properties become excellent due to the crystal grain growthof the α phase, but pressure resistance is low. “κ”/“α” is preferably0.3 or more, and optimally 0.5 or more. Meanwhile, “κ”/“α” exceeds 2,the κ phase becomes excessive, a problem occurs particularly withductility, impact characteristics deteriorate, and improvement ofpressure resistance is also saturated. “κ”/“α” is preferably 1.5 orless, and optimally 1.2 or less. Therefore, 0.2≦“κ”/“α”≦2 and“α”+“κ”≧92, and, furthermore, in order to achieve 0.3≦“κ”/“α”≦1.5,“α”+“κ”≧94 as a preferable range, not only the composition but also thecooling rate after brazing must be sufficiently managed as describedbelow. Furthermore, in order to obtain high pressure resistance,ductility, impact characteristics, and corrosion resistance afterbrazing, the range of the α phase is 30% to 84%, more preferably 35% to78%, and optimally 42% to 72%, and the range of the κ phase is 15% to65%, more preferably 20% to 62%, and optimally 25% to 55%. Meanwhile, ina case in which Sn is included at 0.3 mass % or more and Al is includedat 0.45 mass % or more, the fraction of the γ phase increases, andtherefore, as a preferable metallic structure, 38≦“α”≦84, 15≦“κ”≦60,“α”+“κ”≧92, 0.2≦“κ”/“α”≦1.5, “β”≦1.5, “μ”≦2.5, “β”+“μ”≦3, 0≦“γ”≦7, and0≦“β”+“μ”+“γ”≦8.

The β phase and the μ phase both impair the ductility, corrosionresistance, impact characteristics, and pressure resistance of thebrazed copper alloy. Singularly, when the β phase exceeds 3%, corrosionresistance is adversely influenced, and ductility and impactcharacteristics are also adversely influenced. The β phase is preferably1.5% or less, and optimally 0.5% or less. Meanwhile, when the β phaseexceeds 5%, corrosion resistance, ductility, pressure resistance, andimpact characteristics are adversely influenced. The β phase ispreferably 2.5% or less, and optimally 0.5% or less. Furthermore, thetotal of the area fractions of the β phase and the β phase in themetallic structure must be 6% or less due to an influence on corrosionresistance, ductility, and the like. Preferably, “β”+“μ”≦3, andoptimally “β”+“μ”≦0.5.

The γ phase is α phase that improves machinability before brazing, andis α phase that improves erosion and corrosion resistance after brazingin a case in which Sn and Al are included at an appropriate amount ormore; however, when the area fraction of the γ phase in the metallicstructure exceeds 7% after brazing, ductility, corrosion resistance, andimpact characteristics are adversely influenced. The area fraction ofthe γ phase is preferably 5% or less, and optimally 3% or less. However,pressure resistance improves when a small amount of the γ phase ispresent in a dispersed state. The effect is exhibited when the γ phaseexceeds 0.05%, and, when a small amount of the γ phase is distributed ina dispersed state, ductility or corrosion resistance is not adverselyinfluenced. Therefore, 0≦“γ”≦7, preferably 0≦“γ”5, and optimally0.05≦“γ”3. Furthermore, the fractions of the β phase, the μ phase, andthe γ phase must be evaluated using the total amount thereof. That is,when the total amount of the fractions of the β phase, the μ phase, andthe γ phase exceeds 8%, ductility, corrosion resistance, impactcharacteristics, and pressure resistance after brazing deteriorate. Thetotal amount of the fractions of the β phase, the β phase, and the γphase is preferably 5.5% or less, and optimally 3% or less. That is, thenumeric formula is 0≦“β”+“μ”+“γ”8 preferably 0≦“β”+“μ”+“γ”5.5, andoptimally 0.05≦“β”+“μ”+“γ”3.

Furthermore, the respective phases of α, κ, γ, β, and μ can be definedas follows in a Cu—Zn—Si alloy which is the basis of the invention fromthe quantitative analysis results obtained using an X-ray microanalyzer. The α phase of the matrix includes Cu: 73 mass % to 80 mass %and Si: 1.7 mass % to 3.1 mass % with a remainder of Zn and other addedelements. The typical composition is 76Cu−2.4Si-remainder: Zn. The κphase which is an essential phase includes Cu: 73 mass % to 79 mass %and Si: 3.2 mass % to 4.7 mass % with a remainder of Zn and other addedelements. The typical composition is 76Cu−3.9Si-remainder: Zn. The γphase includes Cu: 66 mass % to 75 mass % and Si: 4.8 mass % to 7.2 mass% with a remainder of Zn and other added elements. The typicalcomposition is 72Cu−6.0Si-remainder: Zn. The β phase includes Cu: 63mass % to 72 mass % and Si: 1.8 mass % to 4.0 mass % with a remainder ofZn and other added elements. The typical composition is69Cu−2.4Si-remainder: Zn. The β phase includes Cu: 76 mass % to 89 mass% and Si: 7.3 mass % to 11 mass % with a remainder of Zn and other addedelements. The typical composition is 83Cu−9.0Si-remainder: Zn. As such,the μ phase is differentiated from the α phase, the κ phase, the γphase, and the β phase using the Si concentration, and the γ phase isdifferentiated from the α phase, the κ phase, the β phase, and the μphase using the Si concentration. The μ phase and the γ phase are closein terms of the content of Si, but are differentiated at the boundary ofa Cu concentration of 76%. The β phase is differentiated from the γphase using the Si concentration, and is differentiated from the αphase, the κ phase, and the μ phase using the Cu concentration. The αphase and the κ phase are close, but are differentiated at the boundaryof a Si concentration of 3.15 mass % or 3.1 mass % to 3.2 mass %. Inaddition, in investigation of the crystal structures using EBSD(electron backscatter diffraction), the α phase is fcc, the β phase isbcc, the γ phase is bcc, and the κ phase is hcp, which can bedifferentiated respectively. Meanwhile, the β phase has a CuZn-form,that is, a W-form bcc structure, and the γ phase has a Cu₅Zn₈-form bccstructure so that both are differentiated. Originally, the crystalstructure of the κ phase: hcp has poor ductility, and, when0.2≦“κ”/“α”≦2 is satisfied in the presence of the a phase, favorableductility is obtained. Furthermore, the fractions of phases in themetallic structure are shown, but non-metallic inclusions, Pb particles,Bi particles, a compound of Ni and Si, and a compound of Mn and Si arenot included.

Next, the cooling rate after brazing will be described. The cooling rateafter brazing is a condition for obtaining high pressure resistance andexcellent corrosion resistance. That is, in order to obtain highpressure resistance and excellent corrosion resistance, it is necessaryto heat a copper alloy such as a valve to 700° C. or higher,furthermore, 750° C. or higher or approximately 800° C. using thebrazing temperature of approximately 800° C., and cool the copper alloyat an average of a cooling rate of 0.1° C./second to 60° C./second intemperature range of the temperature of the copper alloy after the endof brazing to 300° C. or 700° C. to 300° C. When the cooling rate isslower than 0.1° C./second, the μ phase precipitates in crystal grainboundaries, the crystal growth of the α phase and the crystal growth ofthe κ phase, depending on circumstances, occur, and ductility, impactcharacteristics, strength, pressure resistance, and corrosion resistancedegrade. Furthermore, in order to prevent the precipitation of the μphase that has an adverse influence on corrosion resistance and suppressthe crystal grain growth of the α phase and the κ phase which encouragedegradation of pressure resistance, cooling is performed at a coolingrate of preferably 0.8° C./second or more and optimally 1.5° C./secondor more after brazing. Particularly, since the β phase is easilygenerated at 300° C. to 450° C., the copper alloy is preferably cooledat a cooling rate of 0.1° C./second or more in the above temperaturerange. In a temperature area lower than 300° C., the μ phase rarelyprecipitates even when the cooling rate is slower than 0.1° C./second,for example, 0.02° C./second. In addition, the μ phase rarelyprecipitates even when the copper alloy is held for 1 hour atapproximately 250° C. in the cooling process. On the other hand, whenthe cooling rate is faster than 60° C./second, since the β phase remainsto a large extent, corrosion resistance deteriorates, and ductility andimpact characteristics also degrade. In order to eliminate the remainingof the β phase that adversely influences corrosion resistance and thelike, cooling after brazing is preferably performed at a cooling rate of40° C./second or less.

As described above, brazing produces a high joint strength, but has ahigh melting point such that the copper alloy is also heated to a hightemperature, and thus strength and pressure resistance decrease, andcorrosion resistance and other characteristics degrade. Somecopper-based hard solders contain a large amount of Ag. A hard solderincluding several tens of percentage of Ag has an effect of decreasingthe melting point by 100° C. compared to a hard solder including no Ag.However, since Ag is extremely expensive, there is a large problemregarding economic efficiency even when a slight amount of Ag is used.The brazing temperature is approximately 800° C. when a hard solderincluding no Ag or including approximately 10% of Ag is used, and acopper alloy such as a valve is also heated to approximately 800° C., atleast 750° C. or higher. Since a copper alloy is heated to approximately800° C., at least 750° C. or higher during brazing, the cooling rate ofthe brazed copper alloy is 0.8° C./second to 40° C./second, and morepreferably 1.5° C./second to 40° C./second in a temperature range of700° C. to 300° C.

Furthermore, in a case in which a pressure is applied to the innersurface, when t represents the minimum thickness of a pipe, P representsa design pressure, D represents the outer diameter of the pipe, Arepresents the acceptable tensile strength of a material, and brepresents the efficiency of a welded joint,

t=PD/(200Ab+0.8P).

That is, since the pressure P depends on the acceptable tensilestrength, and the acceptable tensile strength depends on the tensilestrength of a material, when the tensile strength of the material ishigh, the material can endure a high pressure. In addition, when theinitial deformation strength of a pressure-resistant vessel becomes aproblem, it is also possible to use proof stress instead of tensilestrength. Therefore, the pressure resistance of the pressure-resistantvessel depends on the tensile strength and proof stress of a brazedmaterial, and the thickness of the pressure-resistant vessel can be thinwhen the values thereof are high so that the pressure-resistant vesselcan be manufactured at low cost. Based on the above, tensile strengthand proof stress can be used as an index that indicates high pressureresistance.

EXAMPLES

Specimens L, M, and N were manufactured using the copper alloys of thefirst to fourth invention alloys and a copper alloy having a compositionfor comparison. Table 1 shows the compositions of the copper alloys ofthe first to fourth invention alloys and the copper alloy forcomparison, which were used to manufacture the specimens. The specimen Lwas obtained by heating an ingot (cylindrical ingot having an outerdiameter of 100 mm and a length of 150 mm) having the composition inTable 1 to 670° C. and extruding the ingot into a round bar shape havingan outer diameter of 17 mm (extruded material). The specimen M wasobtained by heating an ingot (cylindrical ingot having an outer diameterof 100 mm and a length of 150 mm) having the composition in Table 1 to670° C., extruding the ingot into a round bar shape having an outerdiameter of 35 mm, then, heating the rod to 670° C., placing the rodhorizontally, hot forging the rod into a thickness of 17.5 mm, andcutting the hot-forged material into a round bar material having anouter diameter of 17 mm (hot-forged material). The specimen N wasobtained by pouring molten metal having the composition in Table 1 intoa mold having a diameter of 35 mm and a depth of 200 mm, casting themolten metal, cutting the cast molten metal at a lathe so as to have thesame size as the specimen L, and producing a round bar having an outerdiameter of 17 mm (cast material).

TABLE 1 Alloy Alloy composition (mass %) No. Cu Si P Sb As Zn Sn Al PbBi Zr Mn Ni Ti B K* First A11 75.1 3.0 Rem. 64.30 invention alloy SecondA21 77.3 3.3 0.07 Rem. 65.21 invention A22 76.4 3.2 0.04 0.08 Rem. 64.74alloy A23 75.4 3.2 0.09 Rem. 63.61 A24 77.1 2.8 0.07 0.03 Rem. 67.01 A2575.7 3.5 0.08 0.04 Rem. 62.88 A26 77.0 3.0 0.11 0.04 Rem. 0.33 65.86 A2776.6 2.9 Rem. 0.42 0.05 65.65 A28 76.4 3.1 0.06 0.07 Rem. 0.48 0.0664.66 A29 77.1 3.0 0.1 0.05 Rem. 0.35 0.26 mass % of Fe is included65.95 Third A31 75.5 3.1 0.08 Rem. 0.025 64.33 invention A32 77.8 3.20.06 Rem. 0.06 66.34 alloy A33 76.6 2.8 0.08 Rem. 0.63 0.09 65.34 A3478.1 3.2 0.05 Rem. 0.08 0.48 0.03 65.63 Fourth A41 76.5 3.1 0.09 Rem.0.015 0.008 65.09 invention A42 75.2 3.0 0.06 0.03 Rem. 0.03 0.01 64.44alloy A43 77.7 3.3 0.08 0.05 Rem. 0.42 0.005 65.16 A44 73.9 3.4 0.11Rem. 0.12 0.01 1.6 64.98 A45 75.8 3.8 0.08 Rem. 0.75 0.006 1.5 0.3 64.18Comparative 101 78.4 4.2 0.04 Rem. 0.01 63.31 alloy 102 74.0 2.3 0.080.05 Rem. 0.02 65.48 103 77.9 2.7 0.05 0.05 Rem. 68.06 104 75.0 3.7 0.08Rem. 61.44 105 74.1 3.2 0.14 Rem. 0.39 0.12 0.007 61.49 110 85.1 0.03Rem. 4.8 5.3 82.86 111 85.4 0.03 Rem. 5.3 2.2 81.11 112 60.2 0.04 Rem.0.2 3.0 61.49 113 59.0 Rem. 0.2 2.0 59.80 114 67.8 0.05 Rem. 0.6 0.221.6 0.2 67.77 115 63.5 0.09 Rem. 0.8 1.7 63.28 *K = [Cu] − 3.6 × [Si] −3 × [P] − 0.3 × [Sb] + 0.5 × [As] − 1 × [Sn] − 1.9 × [Al] + 0.5 × [Pb] +0.5 × [Bi] + 2 × [Mn] + 1.7 × [Ni] + 1 × [Ti] + 2 × [B] + 2 × [Zr]

The following test 1 or 2 was performed on the respective specimens.Test 1: Each of the specimens was immersed in a salt bath (in which NaCland CaCl₂ were mixed at approximately 3:2) at 800° C. for 100 seconds inorder to simulate a state in which the specimen was heated using aburner during brazing. The specimen was held at approximately 800° C.for approximately 10 seconds during immersion in the salt bath. Inaddition, the specimen was removed and cooled under conditions of watercooling in ice water, water cooling at 10° C., warm water cooling at 60°C., and forcible air cooling A, B, and C (the rate of the fan duringforcible air cooling became faster in the order of A, B, and C). Inaddition, in order to realize a slower cooling rate, the specimen washeated to 800° C. in an inert atmosphere using a continuous furnace(furnace brazing furnace) in which the temperature was increased anddecreased continuously, held for 1 minute, and cooled in the furnaceunder two conditions (conditions D and E). The average cooling ratesfrom 700° C. to 300° C. when the specimen was treated under a variety ofconditions were 70° C./second for water cooling in ice water, 50°C./second for water cooling at 10° C., 35° C./second for warm watercooling at 60° C., 6.0° C./second for forcible air cooling A, 2.5°C./second for forcible air cooling B, 1.2° C./second for forcible aircooling C, 0.15° C./second for the condition D of furnace cooling, and0.02° C./second for the condition E of furnace cooling.

Test 2: The following brazing was performed in order to measure thetensile strength at a brazed portion after the specimens L, M, and Nwere brazed to another material. A copper rod having an outer diameterof 25 mm was prepared as the other material, a hole having an innerdiameter of 18 mm and a depth of 50 mm was formed at the center of theend surface of the copper rod through cutting, each of the specimens L,M, and N was inserted into the hole, a flux was attached to the specimenand the copper rod, the flux was melted through heating using a burnerincluding preheating of the copper rod, and a brazing filler metal wasmade to become easily wet. Immediately afterwards, using a phosphorbronze brazing filler of Cu−7% P(B—CuP2), the brazing filler metal, thespecimen, and the copper rod were heated to approximately 800° C. so asto melt the phosphor bronze brazing filler, and complete attachment ofthe phosphor bronze brazing filler to the joint portion was confirmed,thereby finishing brazing. Immediately afterwards, the specimen wascooled using the same method as for the test 1.

After the test 1 or 2 of the specimens L, M, and N, dezincificationcorrosion properties, erosion and corrosion resistance, tensilestrength, proof stress, elongation, and impact strength were evaluatedin the following manner.

Dezincification corrosion properties were evaluated in the followingmanner based on ISO 6509. A specimen taken from a test material producedusing the method of the test 1 was implanted into a phenol resinmaterial so that the exposed specimen surface became perpendicular tothe extruding direction of the extruded material for the specimen L, wasimplanted in a phenol resin material so that the exposed specimensurface became perpendicular to the longitudinal direction of thehot-forged material or the cast metal for the specimens M and N, thespecimen surfaces were polished using Emery paper of up to No. 1200, thespecimens were ultrasonic-washed in pure water, and dried. After that,each of the specimens was immersed in an aqueous solution (12.7 g/L) of1.0% cupric chloride dehydrate (CuCl₂.2H₂O), held for 24 hours under atemperature condition of 75° C., then, removed from the aqueoussolution, and the maximum value of the dezincification corrosion depth(maximum dezincification corrosion depth) was measured. The specimen wasagain implanted into a phenol resin material so that the exposed surfacewas held perpendicularly to the extruding direction, and then, thespecimen was cut so as to obtain a longest cut portion. Subsequently,the specimen was polished, and corrosion depths were observed usingmetal microscopes with a magnification of 100 times to 500 times at 10points in the field of view of the microscope. The deepest corrosionpoint was recorded as the maximum dezincification corrosion depth.Meanwhile, when the maximum corrosion depth is 200 μm or less in the ISO6509 test, corrosion resistance does not cause a practical problem, and,in a case in which particularly excellent corrosion resistance isrequired, the maximum corrosion depth is desirably 100 μm or less, andmore desirably 50 μm or less.

Erosion and corrosion resistance was evaluated in the following manner.A specimen cut from a test material produced using the method of thetest 1 was used for evaluation of erosion and corrosion resistance. Inthe erosion and corrosion test, a 3% saline solution was impacted on thespecimen at a flow rate of 11 m/second using a nozzle having an caliberof 2 mm, the cross-sectional surface was observed after 168 hours hadelapsed, and the maximum corrosion depth was measured. Since a copperalloy used for a tap water supply valve, and the like, is exposed to anabrupt change in the water flow rate caused by a reverse flow or openingand closing of a valve, not only ordinary corrosion resistance but alsoerosion and corrosion resistance are required.

Tensile strength, proof stress, and elongation were measured usingtensile tests. The shape of a specimen for the tensile test looked likea 14A specimen having a gauge length of JIS Z 2201 of (square root ofthe cross sectional area of the specimen parallel portion)×5.65. For aspecimen obtained by joining a copper rod and the specimen throughbrazing in the test 2, a tensile test was performed on the copper rodand the specimen joined through brazing. Elongation was not measured,but a tensile strength was obtained by dividing a rupture load by thecross-sectional area of a ruptured portion. In the tensile test of thecopper rod and the specimen brazed, the specimens were all ruptured onthe specimen side 10 mm or more away from the brazed portion.

The metallic structure was evaluated by mirror-polishing the horizontalcross-section of the specimen, etching the cross section using a liquidmixture of hydrogen peroxide and aqueous ammonia, and measuring the areafractions (%) of the α phase, the κ phase, the β phase, the γ phase, andthe μ phase through image analyses. That is, the area fractions of therespective phases were obtained by digitalizing optical microscopicstructures with a magnification of 200 times or 500 times using imagetreatment software “WinROOF.” The area fractions were measured at 3points, and the average value was used as the phase ratio of therespective phases. In a case in which it was difficult to identifyphases, phases were specified using an electron back scatteringdiffraction pattern (FE-SEM-EBSP) method, and the area fractions of therespective phases were obtained. A JSM-7000F manufactured by JEOL Ltd.was used as the FE-SEM, an OIM-Ver. 5.1 manufactured by TSL SolutionsLtd. was used for analysis, and phases were obtained from phase mapshaving an analysis magnification of 500 times and 2000 times.

In an impact test, an impact specimen (a V-notch specimen according toJIS Z 224) was taken from the specimen which had undergone a thermaltreatment in a salt bath of the test 1, a Charpy impact test wasperformed, and an impact strength was measured. Machinability wasevaluated in a cutting test in which a lathe was used, which wasperformed using the following method. An extruded specimen having adiameter of 17 mm, a hot-forged specimen, or a cast specimen was cut onthe circumstance of a lathe equipped with a point nose straight tool,particularly, a tungsten carbide tool not equipped with a chip breakerin a dry condition at a rake angle of −6 degrees, a nose radius of 0.4mm, a cutting rate of 100 (m/min), a cutting depth of 1.0 mm, and a feedrate of 0.11 mm/rev. A signal emitted from a dynamometer composed ofthree portions attached to a tool was converted to an electrical voltagesignal, and recorded in a recorder. Next, the signal was converted to acutting resistance (N). Therefore, the machinability of the alloy wasevaluated by measuring cutting resistance, particularly, the maincomponent force showing the highest value during cutting.

The results of the respective tests are shown in Tables 2 to 11. Tables2 and 3, Tables 4 and 5, Tables 6 and 7, Tables 8 and 9, Tables 10 and11, and Tables 12 and form sets, and indicate the results. Since themachinability was evaluated in a state in which the heating of the test1 had not yet been performed, the results are described for each of thespecimens L, M, and N of the respective alloys. The numeric values of 1to 8 in the cooling rate columns in the table represent 1: water coolingin ice water (70° C./second), 2: water cooling at 10° C. (50°C./second), 3: warm water cooling at 60° C. (35° C./second), 4: forcibleair cooling A (6.0° C./second), 5: forcible air cooling B (2.5°C./second), 6: forcible air cooling C (1.2° C./second), 7: condition Dof furnace cooling (0.15° C./second), and 8: condition E of furnacecooling (0.02° C./second). FIGS. 1A to 1C show the metallic structuresof specimens No. A11L2, A21L7, and A26L4 after the test 1 respectively,and FIG. 1C shows the metallic structure of the brazed portion of thespecimen No. A11L6 after the test 2.

TABLE 2 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ A11L1 A11 L 1 50.742.8 1.6 4.9 0 93.5 0.84 4.9 6.5 A11L2 A11 L 2 55 42.4 1.7 0.9 0 97.40.77 0.9 2.6 A11L3 A11 L 3 57.6 40.7 1.7 0 0 98.3 0.71 0 1.7 A11L4 A11 L4 60.3 37.7 2 0 0 98 0.63 0 2 A11L5 A11 L 5 60.7 37.3 2 0 0 98 0.61 0 2A11L6 A11 L 6 61.6 36.4 1.8 0 0.2 98 0.59 0.2 2 A11L7 A11 L 7 61.8 35.41.5 0 1.3 97.2 0.57 1.3 2.8 A11L8 A11 L 8 63.5 28.5 2.2 0 5.8 92 0.455.8 8 A11N2 A11 N 2 54.9 42.4 2 0.7 0 97.3 0.77 0.7 2.7 A11N3 A11 N 356.8 41.2 2 0 0 98 0.73 0 2 A11N5 A11 N 5 59.4 38.8 1.8 0 0 98.2 0.65 01.8 A11N6 A11 N 7 61.7 35.1 1.8 0 1.4 96.8 0.57 1.4 3.2 A11M2 A11 M 254.4 42.5 2.3 0.8 0 96.9 0.78 0.8 3.1 A11M3 A11 M 3 56.5 41.5 2 0 0 980.73 0 2 A11M5 A11 M 5 60 38 2 0 0 98 0.63 0 2 A11M7 A11 M 7 61 35.9 2 01.1 96.9 0.59 1.1 3.1 A21L1 A21 L 1 46.3 49.5 0.2 4 0 95.8 1.07 4 4.2A21L2 A21 L 2 51.4 47.9 0.4 0.3 0 99.3 0.93 0.3 0.7 A21L3 A21 L 3 54.445.1 0.4 0.1 0 99.5 0.83 0.1 0.5 A21L4 A21 L 4 56.3 43.5 0.2 0 0 99.80.77 0 0.2 A21L5 A21 L 5 57.3 42.5 0.2 0 0 99.8 0.74 0 0.2 A21L6 A21 L 658.7 40.7 0.3 0 0.3 99.4 0.69 0.3 0.6 A21L7 A21 L 7 59.4 38.8 0.4 0 1.498.2 0.65 1.4 1.8 A21L8 A21 L 8 60.5 30.5 0.5 0 8.5 91 0.50 8.5 9 A21N2A21 N 2 50.5 48.6 0.6 0.3 0 99.1 0.96 0.3 0.9 A21N3 A21 N 3 54.2 45.30.5 0 0 99.5 0.84 0 0.5 A21N5 A21 N 5 56.8 42.8 0.4 0 0 99.6 0.75 0 0.4A21N7 A21 N 7 59 39 0.5 0 1.5 98 0.66 1.5 2 A21M2 A21 M 2 51.1 47.9 0.50.5 0 99 0.94 0.5 1 A21M3 A21 M 3 54 45.3 0.5 0.2 0 99.3 0.84 0.2 0.7A21M5 A21 M 5 57 42.7 0.3 0 0 99.7 0.75 0 0.3 A21M7 A21 M 7 58.8 39.50.5 0 1.2 98.3 0.67 1.2 1.7 A22L1 A22 L 1 47.6 48 0.8 3.6 0 95.6 1.013.6 4.4 A22L2 A22 L 2 53.2 45.7 0.9 0.2 0 98.9 0.86 0.2 1.1 A22L3 A22 L3 55.7 43.5 0.8 0 0 99.2 0.78 0 0.8 A22L4 A22 L 4 57.3 41.6 1.1 0 0 98.90.73 0 1.1 A22L5 A22 L 5 58.5 40.7 0.8 0 0 99.2 0.70 0 0.8 A22L6 A22 L 659.7 39.1 1 0 0.2 98.8 0.65 0.2 1.2 A22L7 A22 L 7 59.9 38.3 0.9 0 0.998.2 0.64 0.9 1.8 A22L8 A22 L 8 61.5 31.1 1.1 0 6.3 92.6 0.51 6.3 7.4A22N1 A22 N 1 47.2 47.9 1 3.9 0 95.1 1.01 3.9 4.9 A22N2 A22 N 2 52.546.3 0.9 0.3 0 98.8 0.88 0.3 1.2 A22N3 A22 N 3 55 44 1 0 0 99 0.80 0 1A22N4 A22 N 4 57 42.1 0.9 0 0 99.1 0.74 0 0.9 A22N5 A22 N 5 58.2 40.8 10 0 99 0.70 0 1 A22N6 A22 N 6 59 39.6 1.2 0 0.2 98.6 0.67 0.2 1.4 A22N7A22 N 7 59.5 38.5 1 0 1 98 0.65 1 2 A22N8 A22 N 8 61 31.2 1.3 0 6.5 92.20.51 6.5 7.8

TABLE 3 Erosion Cutting Dezincification and Tensile resistance corrosioncorrosion strength (N) Tensile Proof properties resistance after Mainstrength stress Elongation Impact Depth (μm/1 test 2 component Test No.N/mm² N/mm² % J/cm² (μm) week) N/mm² force A11L1 424 215 11 16 380 70407 119 A11L2 440 215 21 19 200 40 440 A11L3 436 207 23 22 140 30 442A11L4 440 203 25 22 140 30 440 A11L5 444 201 26 23 130 25 446 A11L6 430200 25 23 120 30 435 A11L7 435 205 19 20 180 40 437 A11L8 417 215 13 14270 60 415 A11N2 415 182 20 20 190 45 418 A11N3 412 177 24 22 130 30 420A11N5 410 175 25 24 140 30 415 A11N6 413 178 19 20 170 35 405 A11M2 450216 18 20 200 40 445 A11M3 444 220 22 22 120 25 446 A11M5 440 216 24 21130 25 442 A11M7 440 215 17 18 160 35 438 A21L1 467 250 13 17 130 25 121A21L2 480 242 21 22 35 10 A21L3 477 237 25 24 20 8 A21L4 475 235 27 2515 7 A21L5 473 234 28 26 15 7 A21L6 470 233 27 26 20 10 A21L7 480 240 1820 40 15 A21L8 455 262 11 15 85 35 A21N2 455 215 22 23 30 10 124 A21N3450 208 26 25 20 7 A21N5 447 202 28 26 15 7 A21N7 452 207 19 20 35 15A21M2 485 248 21 22 40 15 120 A21M3 483 243 24 23 20 10 A21M5 478 240 2625 15 8 A21M7 484 244 17 20 40 15 A22L1 468 245 15 18 140 30 462 A22L2476 236 21 21 35 10 480 A22L3 470 230 24 23 20 10 468 A22L4 465 228 2624 20 8 464 A22L5 467 230 26 25 20 8 468 A22L6 463 224 25 25 20 10 470A22L7 470 236 18 21 35 15 465 A22L8 449 250 13 16 75 30 445 A22N1 438215 13 18 155 30 434 A22N2 445 205 22 22 40 10 450 A22N3 440 202 25 2420 10 444 A22N4 437 200 25 24 25 10 435 A22N5 440 195 28 25 25 10 440A22N6 437 200 26 25 20 10 442 A22N7 442 198 19 20 40 15 438 A22N8 417214 10 15 75 35 422

TABLE 4 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ A22M1 A22 M 1 47.548.2 0.8 3.5 0 95.7 1.01 3.5 4.3 A22M2 A22 M 2 52.8 46.1 1 0.1 0 98.90.87 0.1 1.1 A22M3 A22 M 3 56 43 1 0 0 99 0.77 0 1 A22M4 A22 M 4 56.542.5 1 0 0 99 0.75 0 1 A22M5 A22 M 5 58 40.8 1.2 0 0 98.8 0.70 0 1.2A22M6 A22 M 6 58.8 40.1 0.9 0 0.2 98.9 0.68 0.2 1.1 A22M7 A22 M 7 59.338.5 1 0 1.2 97.8 0.65 1.2 2.2 A22M8 A22 M 8 60.7 32.1 1.2 0 6 92.8 0.536 7.2 A23L1 A23 L 1 44.5 47.4 2.3 5.8 0 91.9 1.07 5.8 8.1 A23L2 A23 L 250.4 46.6 2.4 0.6 0 97 0.92 0.6 3 A23L3 A23 L 3 52.6 45.2 2.2 0 0 97.80.86 0 2.2 A23L4 A23 L 4 54.8 42.6 2.6 0 0 97.4 0.78 0 2.6 A23L5 A23 L 555.1 42.5 2.4 0 0 97.6 0.77 0 2.4 A23L6 A23 L 6 56.2 41.3 2.4 0 0.1 97.50.73 0.1 2.5 A23L7 A23 L 7 57 40 2.3 0 0.7 97 0.70 0.7 3 A23L8 A23 L 858.4 32.8 2.6 0 6.2 91.2 0.56 6.2 8.8 A24L1 A24 L 1 72.5 24 0 3.5 0 96.50.33 3.5 3.5 A24L2 A24 L 2 75 25 0 0 0 100 0.33 0 0 A24L3 A24 L 3 76.523.2 0.3 0 0 99.7 0.30 0 0.3 A24L4 A24 L 4 77 22.8 0.2 0 0 99.8 0.30 00.2 A24L5 A24 L 5 78.1 21.8 0.1 0 0 99.9 0.28 0 0.1 A24L6 A24 L 6 78.521.1 0.4 0 0 99.6 0.27 0 0.4 A24L7 A24 L 7 79.4 19.2 0.3 0 1.1 98.6 0.241.1 1.4 A24L8 A24 L 8 77.2 13.6 0.2 0 9 90.8 0.18 9 9.2 A25L1 A25 L 137.5 52.1 3 7.4 0 89.6 1.39 7.4 10.4 A25L2 A25 L 2 42.8 53.3 3 1.9 096.1 1.25 1.9 4.9 A25L3 A25 L 3 43.6 52.8 3.5 0.1 0 96.4 1.21 0.1 3.6A25L4 A25 L 4 46 50 4 0 0 96 1.09 0 4 A25L5 A25 L 5 46.5 48.7 4.8 0 095.2 1.05 0 4.8 A25L6 A25 L 6 47.5 47.5 5 0 0 95 1.00 0 5 A25L7 A25 L 748.5 45.1 4.2 0 2.2 93.6 0.93 2.2 6.4 A25L8 A25 L 8 49.5 38.5 3.5 0 8.588 0.78 8.5 12 A26L1 A26 L 1 53 41.5 1.8 3.7 0 94.5 0.78 3.7 5.5 A26L2A26 L 2 58.3 39.5 1.8 0.4 0 97.8 0.68 0.4 2.2 A26L3 A26 L 3 60.9 37.1 20 0 98 0.61 0 2 A26L4 A26 L 4 63.1 34.9 2 0 0 98 0.55 0 2 A26L5 A26 L 564 33.9 2.1 0 0 97.9 0.53 0 2.1 A26L6 A26 L 6 65.5 32.7 1.8 0 0 98.20.50 0 1.8 A26L7 A26 L 7 66.5 30.7 2.1 0 0.7 97.2 0.46 0.7 2.8 A26L8 A26L 8 68 24.3 1.9 0 5.8 92.3 0.36 5.8 7.7

TABLE 5 Erosion Cutting Dezincification and Tensile resistance corrosioncorrosion strength (N) Tensile Proof properties resistance after Mainstrength stress Elongation Impact Depth (μm/1 test 2 component Test No.N/mm² N/mm² % J/cm² (μm) week) N/mm² force A22M1 475 250 14 18 135 25469 A22M2 480 240 20 20 35 10 482 A22M3 477 235 24 23 20 8 472 A22M4 470235 24 23 15 10 475 A22M5 472 230 25 24 15 8 468 A22M6 470 232 26 24 2010 470 A22M7 477 230 20 30 30 12 476 A22M8 453 255 13 16 70 35 448 A23L1A23L2 460 235 16 17 55 25 A23L3 A23L4 A23L5 458 233 21 20 35 15 A23L6A23L7 462 230 17 18 50 20 A23L8 A24L1 A24L2 425 183 30 28 25 10 A24L3420 175 32 30 20 10 A24L4 A24L5 418 167 32 30 20 10 A24L6 A24L7 411 16026 25 25 15 A24L8 A25L1 A25L2 445 245 12 15 80 30 A25L3 452 235 17 18 4015 A25L4 A25L5 445 232 18 17 40 20 A25L6 A25L7 434 250 10 14 65 25 A25L8A26L1 442 233 10 14 125 25 A26L2 454 230 17 18 25 10 A26L3 445 230 20 1920 5 A26L4 450 225 21 20 20 5 A26L5 450 227 21 20 15 4 A26L6 453 225 2120 20 4 A26L7 450 230 16 18 30 10 A26L8 435 242 9 13 60 25

TABLE 6 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ A27L1 A27 L 1 53.239.5 2.3 5 0 92.7 0.74 5 7.3 A27L2 A27 L 2 58.8 38 2.4 0.8 0 96.8 0.650.8 3.2 A27L3 A27 L 3 61.5 36.1 2.4 0 0 97.6 0.59 0 2.4 A27L4 A27 L 463.4 33.9 2.7 0 0 97.3 0.53 0 2.7 A27L5 A27 L 5 65 32.5 2.5 0 0 97.50.50 0 2.5 A27L6 A27 L 6 65.9 31.8 2.3 0 0 97.7 0.48 0 2.3 A27L7 A27 L 767 29.9 2.5 0 0.6 96.9 0.45 0.6 3.1 A27L8 A27 L 8 69.5 23.2 2.3 0 5 92.70.33 5 7.3 A28M1 A28 M 1 49.8 40.7 4 5.5 0 90.5 0.82 5.5 9.5 A28M2 A28 M2 55.4 39.1 4.3 1.2 0 94.5 0.71 1.2 5.5 A28M3 A28 M 3 58.1 37.1 4.5 0.30 95.2 0.64 0.3 4.8 A28M4 A28 M 4 60.3 34.9 4.8 0 0 95.2 0.58 0 4.8A28M5 A28 M 5 61.5 33.5 5 0 0 95 0.54 0 5 A28M6 A28 M 6 62.4 32.8 4.8 00 95.2 0.53 0 4.8 A28M7 A28 M 7 63.8 31.2 4.5 0 0.5 95 0.49 0.5 5 A28M8A28 M 8 66 25.5 4 0 4.5 91.5 0.39 4.5 8.5 A29L2 A29 L 2 58.5 39 2 0.5 097.5 0.67 0.5 2.5 A29L3 A29 L 3 61 36.8 2.2 0 0 97.8 0.60 0 2.2 A29L5A29 L 5 64.9 32.7 2.4 0 0 97.6 0.50 0 2.4 A29L7 A29 L 7 67 30.2 2.1 00.7 97.2 0.45 0.7 2.8

TABLE 7 Erosion Cutting Dezincification and Tensile resistance corrosioncorrosion strength (N) Tensile Proof properties resistance after Mainstrength stress Elongation Impact Depth (μm/1 test 2 component Test No.N/mm² N/mm² % J/cm² (μm) week) N/mm² force A27L1 428 226 10 13 240 35A27L2 445 225 18 16 110 20 A27L3 440 218 20 18 80 8 A27L4 446 215 21 1980 5 A27L5 448 213 22 18 70 5 A27L6 438 210 20 19 70 5 A27L7 440 216 1617 90 10 A27L8 422 229 10 12 120 25 A28M1 408 230 9 11 150 30 A28M2 432226 14 15 100 15 A28M3 442 220 17 17 50 8 A28M4 450 222 20 19 35 3 A28M5452 218 19 18 35 3 A28M6 443 214 20 18 45 5 A28M7 435 216 16 16 60 7A28M8 424 228 8 10 90 15 A29L2 446 230 16 18 25 10 A29L3 444 228 20 2020 6 A29L5 448 235 20 19 20 5 A29L7 443 233 16 17 25 12

TABLE 8 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ A31L1 A31 L 1 49.743.5 1.8 5 0 93.2 0.88 5 6.8 A31L2 A31 L 2 54.4 43 2 0.6 0 97.4 0.79 0.62.6 A31L3 A31 L 3 56.5 41.5 2 0 0 98 0.73 0 2 A31L4 A31 L 4 58.9 39 2.10 0 97.9 0.66 0 2.1 A31L5 A31 L 5 59.6 38.2 2.2 0 0 97.8 0.64 0 2.2A31L6 A31 L 6 60.3 37.5 2.1 0 0.1 97.8 0.62 0.1 2.2 A31L7 A31 L 7 60.936.2 2 0 0.9 97.1 0.59 0.9 2.9 A31L8 A31 L 8 62.6 29.5 2.4 0 5.5 92.10.47 5.5 7.9 A32L1 A32 L 1 52.3 43.8 0.4 3.5 0 96.1 0.84 3.5 3.9 A32L2A32 L 2 57.4 42.3 0.2 0.1 0 99.7 0.74 0.1 0.3 A32L3 A32 L 3 60.2 39.60.2 0 0 99.8 0.66 0 0.2 A32L4 A32 L 4 62.4 37.4 0.2 0 0 99.8 0.60 0 0.2A32L5 A32 L 5 63.3 36.4 0.3 0 0 99.7 0.58 0 0.3 A32L6 A32 L 6 64.7 35.10.1 0 0.1 99.8 0.54 0.1 0.2 A32L7 A32 L 7 66 33.3 0.2 0 0.5 99.3 0.500.5 0.7 A32L8 A32 L 8 67.2 26.7 0.1 0 6 93.9 0.40 6 6.1 A33L1 A33 L 153.8 42 1 3.2 0 95.8 0.78 3.2 4.2 A33L2 A33 L 2 59 39.8 1.2 0 0 98.80.67 0 1.2 A33L3 A33 L 3 61.5 37 1.5 0 0 98.5 0.60 0 1.5 A33L4 A33 L 464.2 34.3 1.5 0 0 98.5 0.53 0 1.5 A33L5 A33 L 5 65 33.4 1.6 0 0 98.40.51 0 1.6 A33L6 A33 L 6 66.3 32.3 1.3 0 0.1 98.6 0.49 0.1 1.4 A33L7 A33L 7 67.2 30.3 1.5 0 1 97.5 0.45 1 2.5 A33L8 A33 L 8 69 22.6 1.4 0 7 91.60.33 7 8.4 A34L1 A34 L 1 51 44.7 0.6 3.7 0 95.7 0.88 3.7 4.3 A34L2 A34 L2 55.2 44 0.7 0.1 0 99.2 0.80 0.1 0.8 A34L3 A34 L 3 58.3 41.2 0.5 0 099.5 0.71 0 0.5 A34L4 A34 L 4 60.5 39 0.5 0 0 99.5 0.64 0 0.5 A34L5 A34L 5 61.5 37.9 0.6 0 0 99.4 0.62 0 0.6 A34L6 A34 L 6 63 36.5 0.5 0 0 99.50.58 0 0.5 A34L7 A34 L 7 64.2 34.8 0.7 0 0.3 99 0.54 0.3 1 A34L8 A34 L 865.5 28.4 0.6 0 5.5 93.9 0.43 5.5 6.1 A34N2 A34 N 2 54.8 44.5 0.6 0.1 099.3 0.81 0.1 0.7 A34N3 A34 N 3 58.2 41.1 0.7 0 0 99.3 0.71 0 0.7 A34N5A34 N 5 61 38.2 0.8 0 0 99.2 0.63 0 0.8 A34N7 A34 N 7 63.5 35.3 0.8 00.4 98.8 0.56 0.4 1.2 A34M2 A34 M 2 55 44.1 0.8 0.1 0 99.1 0.80 0.1 0.9A34M3 A34 M 3 58.1 41.1 0.8 0 0 99.2 0.71 0 0.8 A34M5 A34 M 5 60.8 38.21 0 0 99 0.63 0 1 A34M7 A34 M 7 63.5 35.2 0.8 0 0.5 98.7 0.55 0.5 1.3A41N1 A41 N 1 48.5 47.4 0.6 3.5 0 95.9 0.98 3.5 4.1 A41N2 A41 N 2 54.544.6 0.7 0.2 0 99.1 0.82 0.2 0.9 A41N3 A41 N 3 57 42.3 0.7 0 0 99.3 0.740 0.7 A41N4 A41 N 4 58.2 40.8 1 0 0 99 0.70 0 1 A41N5 A41 N 5 59.5 39.80.7 0 0 99.3 0.67 0 0.7 A41N6 A41 N 6 61 38.1 0.8 0 0.1 99.1 0.62 0.10.9 A41N7 A41 N 7 61.2 37.4 0.7 0 0.7 98.6 0.61 0.7 1.4 A41N8 A41 N 862.6 30.7 0.9 0 5.8 93.3 0.49 5.8 6.7 A42N1 A42 N 1 47.9 46 2.5 3.6 093.9 0.96 3.6 6.1 A42N2 A42 N 2 53.1 43.7 3 0.2 0 96.8 0.82 0.2 3.2A42N3 A42 N 3 55.6 41.5 2.9 0 0 97.1 0.75 0 2.9 A42N4 A42 N 4 57.6 39.43 0 0 97 0.68 0 3 A42N5 A42 N 5 58.3 39 2.7 0 0 97.3 0.67 0 2.7 A42N6A42 N 6 59.7 37.5 2.7 0 0.1 97.2 0.63 0.1 2.8 A42N7 A42 N 7 60.3 36 3 00.7 96.3 0.60 0.7 3.7 A42N8 A42 N 8 61.3 29.5 3.2 0 6 90.8 0.48 6 9.2

TABLE 9 Erosion Cutting Dezincification and Tensile resistance corrosioncorrosion strength (N) Tensile Proof properties resistance after Mainstrength stress Elongation Impact Depth (μm/1 test 2 component Test No.N/mm² N/mm² % J/cm² (μm) week) N/mm² force A31L1 451 235 14 18 135 30100 A31L2 466 225 19 20 50 15 A31L3 460 226 23 23 30 10 A31L4 455 220 2422 30 10 A31L5 458 222 24 23 30 10 A31L6 455 225 24 22 30 12 A31L7 460222 18 20 45 15 A31L8 444 235 14 17 85 25 A32L1 433 222 18 19 120 35 103A32L2 440 212 27 25 20 10 A32L3 435 204 30 27 15 10 A32L4 437 207 33 2915 10 A32L5 435 205 32 28 15 10 A32L6 438 205 32 28 15 10 A32L7 439 21030 26 20 10 A32L8 426 220 16 18 70 25 A33L1 453 230 16 19 135 20 A33L2457 225 24 24 30 3 A33L3 450 215 26 25 20 2 A33L4 453 222 24 24 20 2A33L5 450 220 26 24 20 2 A33L6 447 215 26 25 20 2 A33L7 456 225 19 20 405 A33L8 436 233 12 15 80 20 A34L1 466 252 14 17 130 20 107 A34L2 472 24420 21 35 5 475 A34L3 465 238 24 23 25 3 A34L4 470 235 25 24 25 3 A34L5467 236 25 24 25 2 466 A34L6 463 233 24 25 25 3 A34L7 472 235 20 22 30 5473 A34L8 452 254 13 17 60 15 A34N2 443 215 22 23 35 3 440 105 A34N3 435210 25 24 25 2 A34N5 436 207 25 24 30 3 432 A34N7 442 205 20 21 35 5 440A34M2 475 252 19 20 35 5 482 106 A34M3 470 244 24 24 30 3 A34M5 472 24224 23 25 3 468 A34M7 478 244 20 21 30 5 475 A41N1 438 210 16 18 130 30103 A41N2 444 205 20 20 30 10 A41N3 435 200 22 21 20 10 A41N4 440 200 2423 20 8 A41N5 435 203 23 22 20 10 A41N6 438 198 24 23 20 10 A41N7 440208 19 21 35 15 A41N8 415 215 11 18 70 25 A42N1 A42N2 433 200 20 18 3520 A42N3 A42N4 A42N5 420 190 22 20 30 15 A42N6 A42N7 425 192 18 18 45 25A42N8

TABLE 10 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ A43N1 A43 N 1 49.245.4 1.6 3.8 0 94.6 0.92 3.8 5.4 A43N2 A43 N 2 54.5 43.2 1.8 0.5 0 97.70.79 0.5 2.3 A43N3 A43 N 3 56.8 41.4 1.8 0 0 98.2 0.73 0 1.8 A43N4 A43 N4 59.2 39.1 1.7 0 0 98.3 0.66 0 1.7 A43N5 A43 N 5 59.7 38.4 1.9 0 0 98.10.64 0 1.9 A43N6 A43 N 6 61.2 37 1.8 0 0 98.2 0.60 0 1.8 A43N7 A43 N 763 34.7 1.7 0 0.6 97.7 0.55 0.6 2.3 A43N8 A43 N 8 64.3 29 1.5 0 5.2 93.30.45 5.2 6.7 A44L1 A44 L 1 50.8 42.5 0.8 4.1 0 93.3 0.84 4.1 4.9 A44L2A44 L 2 55.9 40.8 0.9 0.6 0 96.7 0.73 0.6 1.5 A44L3 A44 L 3 57.8 39.50.8 0 0 97.3 0.68 0 0.8 A44L4 A44 L 4 60 37.3 1.1 0 0 97.3 0.62 0 1.1A44L5 A44 L 5 61 36.5 0.8 0 0 97.5 0.60 0 0.8 A44L6 A44 L 6 63 34.5 1 00.1 97.5 0.55 0.1 1.1 A44L7 A44 L 7 63 33.8 0.9 0 0.4 96.8 0.54 0.4 1.3A44L8 A44 L 8 64 27.8 1.1 0 5.8 91.8 0.43 5.8 6.9 A45L1 A45 L 1 42.247.8 0.8 7.6 0 90 1.13 7.6 8.4 A45L2 A45 L 2 48.3 48 0.9 1.1 0 96.3 0.991.1 2 A45L3 A45 L 3 50.2 47.3 0.8 0.1 0 97.5 0.94 0.1 0.9 A45L4 A45 L 452 45.4 1.1 0 0 97.4 0.87 0 1.1 A45L5 A45 L 5 54.1 43.5 0.8 0 0 97.60.80 0 0.8 A45L6 A45 L 6 54.8 42.7 1 0 0 97.5 0.78 0 1 A45L7 A45 L 754.9 42.1 0.9 0 0.5 97 0.77 0.5 1.4 A45L8 A45 L 8 56.1 36.2 1.1 0 5 92.30.65 5 6.1 A45N2 A45 N 2 48 48.1 1 1.2 0 96.1 1.00 1.2 2.2 A45N5 A45 N 553.5 44 0.8 0 0 97.5 0.82 0 0.8 A45N7 A45 N 7 54.2 42.8 1 0 0.4 97 0.790.4 1.4 A45M2 A45 M 2 47.8 48.3 1.1 1.1 0 96.1 1.01 1.1 2.2 A45M5 A45 M5 53.5 43.9 1 0 0 97.4 0.82 0 1 A45M7 A45 M 7 54.3 42.5 0.9 0 0.6 96.80.78 0.6 1.5 101N1 101 1 18 72 2 8 0 90 4.00 8 10 101N2 101 N 2 23.272.8 1.2 2.8 0 96 3.14 2.8 4 101N3 101 N 3 25.2 74.3 0.5 0 0 99.5 2.95 00.5 101N4 101 N 4 28.7 70.8 0.5 0 0 99.5 2.47 0 0.5 101N5 101 N 5 30.569 0.5 0 0 99.5 2.26 0 0.5 101N6 101 6 31.2 67.8 1 0 0 99 2.17 0 1 101N7101 N 7 30.6 66.8 0.8 0 1.8 97.4 2.18 1.8 2.6 101N8 101 8 31.7 61.2 0.70 6.4 92.9 1.93 6.4 7.1 102L1 102 1 75.5 2 4.5 18 0 77.5 0.03 18 22.5102L2 102 L 2 78.5 2 6.5 13 0 80.5 0.03 13 19.5 102L3 102 L 3 78.7 5.110.2 6 0 83.8 0.06 6 16.2 102L4 102 L 4 79 6.5 12 2.5 0 85.5 0.08 2.514.5 102L5 102 L 5 81.5 5 13.5 0 0 86.5 0.06 0 13.5 102L6 102 6 79 8 130 0 87 0.10 0 13 102L7 102 L 7 81.5 6 12 0 0.5 87.5 0.07 0.5 12.5 102L8102 8 80 7.5 10.5 0 2 87.5 0.09 2 12.5 103L1 103 L 1 80 16.5 0 3.5 096.5 0.21 3.5 3.5 103L2 103 L 2 85.5 14 0 0.5 0 99.5 0.16 0.5 0.5 103L3103 L 3 86.8 13.2 0 0 0 100 0.15 0 0 103L4 103 L 4 86.8 13 0.2 0 0 99.80.15 0 0.2 103L5 103 L 5 87.2 12.4 0.4 0 0 99.6 0.14 0 0.4 103L6 103 L 688 11.5 0.3 0 0.2 99.5 0.13 0.2 0.5 103L7 103 L 7 87.4 11 0.1 0 1.5 98.40.13 1.5 1.6 103L8 103 L 8 86.2 9.2 0.1 0 4.5 95.4 0.11 4.5 4.6

TABLE 11 Erosion Cutting Dezincification and Tensile resistancecorrosion corrosion strength (N) Tensile Proof properties resistanceafter Main strength stress Elongation Impact Depth (μm/1 test 2component Test No. N/mm² N/mm² % J/cm² (μm) week) N/mm² force A43N1A43N2 452 225 17 18 45 7 A43N3 448 213 21 20 25 3 A43N4 A43N5 445 215 2321 30 3 A43N6 A43N7 453 224 16 18 45 10 A43N8 A44L1 A44L2 463 239 15 2145 25 A44L3 455 235 20 26 40 20 A44L4 A44L5 450 232 22 27 35 15 A44L6A44L7 457 237 17 23 50 20 A44L8 A45L1 444 249 8 16 180 35 A45L2 482 25417 24 45 20 A45L3 478 250 21 28 30 15 A45L4 470 242 22 30 25 10 A45L5475 247 22 30 20 10 A45L6 477 245 20 29 25 10 A45L7 483 252 16 25 45 15A45L8 448 265 9 17 90 35 A45N2 450 225 18 24 40 15 A45N5 441 219 23 2820 10 A45N7 447 222 16 24 40 15 A45M2 486 260 17 23 40 20 A45M5 480 25221 30 20 10 A45M7 482 250 16 24 50 15 101N1 146 101N2 438 268 4 13 18035 101N3 101N4 101N5 430 260 8 17 110 25 101N6 101N7 447 270 4 10 140 30101N8 102L1 137 102L2 363 142 11 19 650 120 102L3 102L4 102L5 385 139 2422 350 50 102L6 102L7 381 136 23 21 400 75 102L8 103L1 389 148 18 21 18080 103L2 380 142 24 23 50 35 382 103L3 373 138 26 27 35 25 103L4 375 13528 30 30 25 103L5 375 140 27 28 30 25 373 103L6 368 132 28 30 35 25103L7 377 140 26 27 55 35 375 103L8 364 144 15 22 100 70

TABLE 12 Test Alloy Cooling Area fraction (%) Computation result No. No.Specimen rate α κ γ β μ α + κ κ/α β + μ β + μ + γ 104L1 104 L 1 24.5 583.5 14 0 82.5 2.37 14 17.5 104L2 104 L 2 27.8 56 6.7 9.5 0 83.8 2.01 9.516.2 104L3 104 L 3 31.2 58.3 8 2.5 0 89.5 1.87 2.5 10.5 104L4 104 L 435.9 56.3 7.3 0.5 0 92.2 1.57 0.5 7.8 104L5 104 L 5 36 55 9 0 0 91 1.530 9 104L6 104 L 6 37.5 54.3 8.2 0 0 91.8 1.45 0 8.2 104L7 104 L 7 3850.8 8.5 0 2.7 88.8 1.34 2.7 11.2 104L8 104 L 8 38.5 45.5 7 0 9 84 1.189 16 105N5 105 N 5 38 49.5 12.5 0 0 87.5 1.30 0 12.5 110N5 110 N 5 96 00 0 0 — — — — 111N5 111 N 5 98.1 0 0 0 0 — — — — 112L1 112 L 1 20.9 0 077 0 — — 77 77 112L2 112 L 2 32.9 0 0 65 0 — — 65 65 112L3 112 L 3 47.80 0 50 0 — — 50 50 112L4 112 L 4 72.4 0 0 25.5 0 — — 25.5 25.5 112L5 112L 5 79.4 0 0 18.4 0 — — 18.4 18.4 112L6 112 L 6 84.3 0 0 13.6 0 — — 13.613.6 112L7 112 L 7 88.4 0 0 9.5 0 — — 9.5 9.5 112L8 112 L 8 90.2 0 0 7.70 — — 7.7 7.7 113M1 113 M 1 0 0 0 98.5 0 — — 98.5 98.5 113M2 113 M 214.5 0 0 84.0 0 — — 84 84 113M3 113 M 3 31.6 0 0 67.0 0 — — 67 67 113M4113 M 4 59 0 0 39.6 0 — — 39.6 39.6 113M5 113 M 5 67.5 0 0 31.0 0 — — 3131 113M6 113 M 6 74.5 0 0 24.0 0 — — 24 24 113M7 113 M 7 79.5 0 0 19.1 0— — 19.1 19.1 113M8 113 M 8 81 0 0 17.5 0 — — 17.5 17.5 114N1 114 N 194.3 0 0 4.5 0 — — 4.5 4.5 114N2 114 N 2 95.1 0 0.1 3.7 0 — — 3.7 3.8114N3 114 N 3 95.6 0 0 3.2 0 — — 3.2 3.2 114N4 114 N 4 97.4 0 0.1 1.4 0— — 1.4 1.5 114N5 114 N 5 97.5 0 0.2 1.1 0 — — 1.1 1.3 114N6 114 N 697.8 0 0.2 0.9 0 — — 0.9 1.1 114N7 114 N 7 97.9 0 0.3 0.6 0 — — 0.6 0.9114N8 114 N 8 98.1 0 0.4 0.4 0 — — 0.4 0.8 115L1 115 L 1 64.6 0 0.1 34.10 — — 34.1 34.2 115L2 115 L 2 74.3 0 0.2 24.3 0 — — 24.3 24.5 115L3 115L 3 80.9 0 0.3 17.5 0 — — 17.5 17.8 115L4 115 L 4 89.3 0 0.3 9.2 0 — —9.2 9.5 115L5 115 L 5 91.9 0 0.5 6.3 0 — — 6.3 6.8 115L6 115 L 6 94.1 00.5 4.2 0 — — 4.2 4.7 115L7 115 L 7 95.3 0 0.7 2.7 0 — — 2.7 3.4 115L8115 L 8 96 0 1 1.8 0 — — 1.8 2.8

TABLE 13 Erosion Cutting Dezincification and Tensile resistancecorrosion corrosion strength (N) Tensile Proof properties resistanceafter Main strength stress Elongation Impact Depth (μm/1 test 2component Test No. N/mm² N/mm² % J/cm² (μm) week) N/mm² force 104L1104L2 458 278 2 11 550 60 104L3 480 270 5 14 280 40 104L4 104L5 472 2638 17 190 35 104L6 104L7 465 272 5 15 260 55 104L8 105N5 395 190 4 13 15045 390 110N5 220 82 16 26 10 5 111N5 195 81 14 23 10 7 100 112L1 381 13718 21 950 130 112L2 373 130 22 22 900 120 370 112L3 371 123 25 24 950120 112L4 364 120 26 24 900 130 112L5 368 122 28 25 850 110 365 112L6366 120 28 25 800 115 112L7 360 121 29 24 800 120 362 112L8 354 116 2725 850 120 113M1 98 113M2 388 124 16 19 800 120 113M3 113M4 113M5 381117 24 24 950 130 113M6 113M7 278 115 23 25 900 120 113M8 114N1 104114N2 335 101 28 23 450 60 114N3 114N4 114N5 328 97 30 26 230 40 114N6114N7 316 88 36 29 110 40 311 114N8 308 80 31 27 40 45 298 115L1 103115L2 347 110 28 25 670 60 115L3 115L4 115L5 336 103 27 24 380 45 115L6115L7 327 94 34 28 190 20 325 115L8 315 87 29 24 70 25 309

From the results of the tests, the following was found. In the first tofour invention alloys, for the respective specimens for which thecooling rate was 0.15° C./second to 50° C./second after being brazed tothe specimens L (extruded material), M (hot-forged material), and N(cast material), the area fractions of the respective phases in themetallic structure satisfied relationships of 30≦“α”≦84, 15≦“κ”≦65,“α”+“κ”≧92, 0.2≦“κ”/“α”≦2, 0≦“β”≦3, 0“μ”≦5, 0≦“β”+“μ”≦6, 0≦“γ”≦7, and0≦“δ”+“μ”+“γ”≦8. In addition, the respective specimens showed a highpressure resistance of 400 N/mm² or more in terms of tensile strengthand 150 N/mm² or more in terms of proof stress. In addition, therespective specimens were favorable in terms of dezincificationcorrosion properties and erosion and corrosion resistance, and showedexcellent corrosion resistance (refer to the respective test resultshaving a cooling rate of 2 to 7 in Alloy Nos. All, A21 to A26, A31 toA34, and A41 to A45).

Compared to the first invention alloy, the second invention alloy wasfavorable in terms of erosion and corrosion resistance and corrosionresistance (refer to the respective test results having a cooling rateof 2 to 7 in Alloy Nos. A11 and A21 to A26).

The third invention alloy contained a small amount of Pb and Bi, and hadalmost the same machinability as a cast metal containing 2.2 mass % Bi(Alloy No. 111) or an extruded rod material containing 1.7 mass % Pb(Alloy No. 115). However, when the composition falls outside of theranges of the present application, favorable machinability cannot beobtained even when a small amount of Pb is included.

Compared to the first invention alloy, the fourth invention alloy hadhigh tensile strength, proof stress, and strength (refer to therespective test results having a cooling rate of 2 to 7 in Alloy Nos.A11 and A41 to A45).

The influence of the cooling rate will be described. In the inventionalloys, at the fastest cooling rate of 70° C./second, the β phaseremained, and the tensile strength and the proof stress were high sothat the pressure resistance was sufficiently satisfactory, but theelongation and the impact strength were low such that the ductility andthe toughness were poor. In addition, the dezincification corrosionproperties, the erosion and corrosion resistance were low, and thecorrosion resistance was poor. However, when the cooling rate becomes50° C./second, remaining of the β phase significantly decreases, andelongation, impact strength, dezincification corrosion properties, anderosion and corrosion resistance significantly improve, and there is noproblem when the cooling rate becomes 35° C./second (refer to therespective test results in Alloy Nos. A11L1, A11L2, A11L3, and thelike).

In the invention alloys, at a slow cooling rate of 0.02° C./second, thearea fraction of the μ phase increased. When the area fraction of the μphase increases, similarly to a case in which the area fraction of the βphase increases, the tensile strength and the proof stress increase, andthe pressure resistance becomes satisfactory, but the elongation and theimpact value are low, and the ductility and the toughness are poor. Inaddition, the dezincification corrosion properties and the erosion andcorrosion resistance were low, and the corrosion resistance was poor.However, when the cooling rate becomes 0.15° C./second, generation ofthe β phase significantly decreases, and the elongation, the impactstrength, the dezincification corrosion properties, and the erosion andcorrosion resistance significantly improve, whereby there is no problemwhen the cooling rate becomes 1.0° C./second (refer to the respectivetest results in Alloy Nos. A11L8, A11L7, A11L6, and the like).

Meanwhile, in the metallic structure, when “α”+“κ”≧94 and0.3≦“κ”/“α”≦1.5, the balance between tensile strength and proof stress,and elongation, impact value, ductility, and toughness became morefavorable, which resulted in dezincification corrosion properties anderosion and corrosion resistance becoming more favorable, and,furthermore, when “α”+“κ”≧95 and 0.5≦“κ”/“α”≦1.2, a more favorableresult was obtained. In addition, when relationships of “β”+“μ”≦3,0≦“γ”≦5, and 0≦“β”+“μ”+“γ”≦5.5 were satisfied, tensile strength,elongation, impact value, ductility, toughness, dezincificationcorrosion properties, and erosion and corrosion resistance became morefavorable, and, when “β”+“μ”0.5, 0.05“γ”3, and 0.05“β”+“μ”+“γ”≦3, thecharacteristics became more favorable. Conversely, when “α”+“κ”<92within the composition range of the invention alloy, elongation, impactvalue, ductility, and toughness were poor, proof stress was high, butductility was low, and therefore tensile strength was low. When“κ”/“α”<0.2, tensile strength and proof stress were low, and, when“κ”/“α”>2, elongation, impact value, ductility, and toughness were poor.In addition, proof stress was high, but ductility was low, and thereforetensile strength was low. When “β”+“μ”>6, “γ”>7, or “β”+“μ”+“γ”>8,elongation, impact value, ductility, toughness, dezincificationcorrosion properties, and erosion and corrosion resistance were poor. Inaddition, proof stress was high, but ductility was low, and thereforetensile strength was low.

When the K value is between 63.0 and 66.5 even within a range of 62.0 to67.5, tensile strength, proof stress, elongation, impact strength,dezincification corrosion properties, and erosion and corrosionresistance become more favorable (refer to the respective test resultsof Alloy Nos. A21, A22, A23, A26, A24, A25, and the like).

When the dezincification corrosion properties of alloys including no Sb,P, and As satisfies the relational formula regarding the phases of themetallic structure, no practical problem occurs; however, in a case inwhich more favorable dezincification corrosion properties are required,inclusion of Sb, P, and As is required. When 0.3 mass % or more of Snand 0.45 mass % or more of Al are included, erosion and corrosionresistance becomes more favorable, and, in combination with theinclusion of Sb, P, and As, furthermore, excellent dezincificationcorrosion properties and erosion and corrosion resistance are obtained.However, since inclusion of Sn and Al precipitates the γ phase to alarge extent, the K value or the Cu concentration is preferably set tobe within or slightly higher than the range of the application (refer tothe respective test results of Alloy Nos. A26, A27, A28, A33, A34, A45,and the like).

When the Si concentration is higher than 4.0 mass %, which is the upperlimit value of the range of the invention alloy, ductility and corrosionresistance are poor (refer to the respective test results of Alloy Nos.101 and the like).

When the Si concentration is lower than 2.5 mass %, which is the lowerlimit value of the range of the invention alloy, proof stress andtensile strength are low, and corrosion resistance is poor (refer to therespective test result of Alloy No. 102 and the like). It was confirmedthat, when Fe is included at 0.26 mass % as an impurity, there is nosignificant change in the metallic structure after brazing and variouscharacteristics (refer to the respective test results of Alloy Nos. A29and the like).

When the Cu concentration and the Si concentration are within the rangesof the invention alloy, but the K value is higher than the upper limitvalue of a range of 62.0 to 67.5, proof stress and tensile strength arelow even when the cooling rate is changed (refer to the respective testresults of Alloy Nos. 103 and the like).

When the Cu concentration and the Si concentration are within the rangesof the invention alloy, but the K value is lower than the lower limitvalue of a range of 62.0 to 67.5, ductility, toughness, and corrosionresistance are poor even when the cooling rate is changed (refer to therespective test results of Alloy Nos. 104, 105, and the like).

The tensile strength from the salt bath test of the test 1 and thetensile strength from the brazing test of the test 2 indicated almostthe same values. Therefore, it was determined that the invention alloyswhich indicated favorable results in the salt bath test of the test 1had high proof stress and tensile strength even when being heated to abrazing temperature of 800° C., and were excellent in terms ofductility, toughness, and corrosion resistance even when a specialthermal treatment was not performed after brazing.

Furthermore, the invention is not limited to the configuration of theabove embodiments, and various modifications are allowed within thescope of the purports of the invention.

The application claims priority based on Japanese Patent Application No.2010-238311, and the content thereof is incorporated herein byreference.

INDUSTRIAL APPLICABILITY

As described above, since the pressure resistant and corrosion resistantcopper alloy according to the invention has high pressure resistance andexcellent corrosion resistance, the pressure resistant and corrosionresistant copper alloy is preferable for brazed vessels, tools, andmembers, such as a variety of valves including a high-pressure valve, aplug valve, a hood valve, a diaphragm valve, a bellows valve, and acontrol valve; a variety of joints such as a pipe joint, a T-shapejoint, a tee (T-type) pipe, and an elbow pipe; a variety of valves suchas a cold and warm water valve, a low-temperature valve, areduced-pressure valve, a high-temperature valve, and a safety valve;hydraulic containers such as joints and cylinders; nozzles, sprinklers,water faucet clasps, and the like as vessels, tools, and members ofhigh-pressure gas facilities, air-conditioning facilities, cold andhot-water supply facilities, and the like.

1. A pressure resistant and corrosion resistant copper alloy brazed toanother material, wherein the copper alloy has an alloy compositioncomprising: 73.0 mass % to 79.5 mass % of Cu; and 2.5 mass % to 4.0 mass% of Si, with a remainder comprising Zn and inevitable impurities,wherein the content of Cu [Cu] mass % and the content of Si [Si] mass %have a relationship of 62.0≦[Cu]−3.6×[Si]≦67.5, and a metallic structureat a brazed portion of the copper alloy includes at least a κ phase inan α phase matrix, and an area fraction of the α phase “α”%, an areafraction of a β phase “δ”%, an area fraction of a γ phase “γ”%, an areafraction of the κ phase “κ”%, and an area fraction of a μ phase “μ”%satisfy the relationships 30≦“α”84, 15≦“κ”≦68, “α”+“κ”≧92, 0.2≦“κ”/“α”2,0≦“β”≦3, 0≦“μ”≦5, 0≦“β”+“μ”≦6, 0≦“γ”≦7, and 0≦“β”+“μ”+“γ”≦8.
 2. Thepressure resistant and corrosion resistant copper alloy according toclaim 1, further comprising at least one additional component selectedfrom the group consisting of 0.015 mass % to 0.2 mass % of P, 0.015 mass% to 0.2 mass % of Sb, 0.015 mass % to 0.15 mass % of As, 0.03 mass % to1.0 mass % of Sn, and 0.03 mass % to 1.5 mass % of Al, wherein thecontent of Cu [Cu] mass %, the content of Si [Si] mass %, the content ofP [P] mass %, the content of Sb [Sb] mass %, the content of As [As] mass%, the content of Sn [Sn] mass %, and the content of Al [Al] mass %satisfy the relationship of62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.
 3. Thepressure resistant and corrosion resistant copper alloy according toclaim 1, further comprising at least one additional component selectedfrom the group consisting of 0.015 mass % to 0.2 mass % of P, 0.015 mass% to 0.2 mass % of Sb, and 0.015 mass % to 0.15 mass % of As, and atleast one additional component selected from the group consisting of 0.3mass % to 1.0 mass % of Sn and 0.45 mass % to 1.2 mass % of Al, whereinthe content of Cu [Cu] mass %, the content of Si [Si] mass %, thecontent of P [P] mass %, the content of Sb [Sb] mass %, the content ofAs [As] mass %, the content of Sn [Sn] mass %, and the content of Al[Al] mass % satisfy the relationship of63.5≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.
 4. Thepressure resistant and corrosion resistant copper alloy according toclaim 1, further comprising at least one additional component selectedfrom the group consisting of 0.003 mass % to 0.25 mass % of Pb and 0.003mass % to 0.30 mass % of Bi, wherein the content of Cu [Cu] mass %, thecontent of Si [Si] mass %, the content of P [P] mass %, the content ofSb [Sb] mass %, the content of As [As] mass %, the content of Sn [Sn]mass %, the content of Al [Al] mass %, the content of Pb [Pb] mass %,and the content of Bi [Bi] mass % satisfy the relationship of62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]≦67.5.
 5. Thepressure resistant and corrosion resistant copper alloy according toclaim 1, further comprising at least one additional component selectedfrom the group consisting of 0.05 mass % to 2.0 mass % of Mn, 0.05 mass% to 2.0 mass % of Ni, 0.003 mass % to 0.3 mass % of Ti, 0.001 mass % to0.1 mass % of B, and 0.0005 mass % to 0.03 mass % of Zr, wherein thecontent of Cu [Cu] mass %, the content of Si [Si] mass %, the content ofP [P] mass %, the content of Sb [Sb] mass %, the content of As [As] mass%, the content of Sn [Sn] mass %, the content of Al [Al] mass %, thecontent of Pb [Pb] mass %, the content of Bi [Bi] mass %, the content ofMn [Mn] mass %, the content of Ni [Ni] mass %, the content of Ti [Ti]mass %, the content of B [B] mass %, and the content of Zr [Zr] mass %satisfy the relationship of62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]+2×[Mn]+1.7×[Ni]+1×[Ti]+2×[B]+2×[Zr]≦67.5.6. The pressure resistant and corrosion resistant copper alloy accordingto claim 1, wherein a material strength of the copper alloy is 400 N/mm²or more in terms of tensile strength or 150 N/mm² or more in terms ofproof stress of the copper alloy.
 7. A brazed structure comprising: (a)the pressure resistant and corrosion resistant copper alloy according toclaim 1; (b) an other material brazed to the copper alloy; and (c) abrazing filler metal that brazes the copper alloy and the othermaterial.
 8. (canceled)
 9. (canceled)
 10. The pressure resistant andcorrosion resistant copper alloy according to claim 2, furthercomprising at least one additional component selected from the groupconsisting of 0.003 mass % to 0.25 mass % of Pb and 0.003 mass % to 0.30mass % of Bi, wherein the content of Cu [Cu] mass %, the content of Si[Si] mass %, the content of P [P] mass %, the content of Sb [Sb] mass %,the content of As [As] mass %, the content of Sn [Sn] mass %, thecontent of Al [Al] mass %, the content of Pb [Pb] mass %, and thecontent of Bi [Bi] mass % satisfy the relationship of62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]≦67.5.11. The pressure resistant and corrosion resistant copper alloyaccording to claim 2, further comprising at least one additionalcomponent selected from the group consisting of 0.05 mass % to 2.0 mass% of Mn, 0.05 mass % to 2.0 mass % of Ni, 0.003 mass % to 0.3 mass % ofTi, 0.001 mass % to 0.1 mass % of B, and 0.0005 mass % to 0.03 mass % ofZr, wherein the content of Cu [Cu] mass %, the content of Si [Si] mass%, the content of P [P] mass %, the content of Sb [Sb] mass %, thecontent of As [As] mass %, the content of Sn [Sn] mass %, the content ofAl [Al] mass %, the content of Pb [Pb] mass %, the content of Bi [Bi]mass %, the content of Mn [Mn] mass %, the content of Ni [Ni] mass %,the content of Ti [Ti] mass %, the content of B [B] mass %, and thecontent of Zr [Zr] mass % satisfy the relationship of62.0≦[Cu]−3.6×[Si]−3×[P]−0.3×[Sb]+0.5×[As]−1×[Sn]−1.9×[Al]+0.5×[Pb]+0.5×[Bi]+2×[Mn]+1.7×[Ni]+1×[Ti]+2×[B]+2×[Zr]≦67.5.12. The pressure resistant and corrosion resistant copper alloyaccording to claim 2, wherein a material strength of the copper alloy is400 N/mm² or more in terms of tensile strength or 150 N/mm² or more interms of proof stress of the copper alloy.
 13. The pressure resistantand corrosion resistant copper alloy according to claim 3, wherein amaterial strength of the copper alloy is 400 N/mm² or more in terms oftensile strength or 150 N/mm² or more in terms of proof stress of thecopper alloy.
 14. The pressure resistant and corrosion resistant copperalloy according to claim 4, wherein a material strength of the copperalloy is 400 N/mm² or more in terms of tensile strength or 150 N/mm² ormore in terms of proof stress of the copper alloy.
 15. The pressureresistant and corrosion resistant copper alloy according to claim 5,wherein a material strength of the copper alloy is 400 N/mm² or more interms of tensile strength or 150 N/mm² or more in terms of proof stressof the copper alloy.
 16. The pressure resistant and corrosion resistantcopper alloy according to claim 10, wherein a material strength of thecopper alloy is 400 N/mm² or more in terms of tensile strength or 150N/mm² or more in terms of proof stress of the copper alloy.
 17. Thepressure resistant and corrosion resistant copper alloy according toclaim 11, wherein a material strength of the copper alloy is 400 N/mm²or more in terms of tensile strength or 150 N/mm² or more in terms ofproof stress of the copper alloy.
 18. A brazed structure comprising: 2.pressure resistant and corrosion resistant copper alloy according toclaim 2; (b) an other material brazed to the copper alloy; and (c) abrazing filler metal that brazes the copper alloy and the othermaterial.
 19. A brazed structure comprising: (a) the pressure resistantand corrosion resistant copper alloy according to claim 3; (b) an othermaterial brazed to the copper alloy; and (c) a brazing filler metal thatbrazes the copper alloy and the other material.
 20. A brazed structurecomprising: (a) the pressure resistant and corrosion resistant copperalloy according to claim 4; (b) an other material brazed to the copperalloy; and (c) a brazing filler metal that brazes the copper alloy andthe other material.
 21. A brazed structure comprising: (a) the pressureresistant and corrosion resistant copper alloy according to claim 5; (b)an other material brazed to the copper alloy; and (c) a brazing fillermetal that brazes the copper alloy and the other material.
 22. A brazedstructure comprising: (a) the pressure resistant and corrosion resistantcopper alloy according to claim 10; (b) an other material brazed to thecopper alloy; and (c) a brazing filler metal that brazes the copperalloy and the other material.
 23. A brazed structure comprising: (a) thepressure resistant and corrosion resistant copper alloy according toclaim 11; (b) an other material brazed to the copper alloy; and (c) abrazing filler metal that brazes the copper alloy and the othermaterial.